Harv's grey motor magneto thread

[Harv]

Ladies and gents,

I've been stashing away info on grey motor maggies for a while. They seem to be a bit like Norman superchargers - rare, cool, hard to understand, multiple variants and full of myths (with a fair sprinkling of bullshit). I'm going to use the thread below to store the info I have to hand, and some of the learnings I've had in fiddling with my maggie.

Like my grey motor Yella Terra head thread, I don't think this will end up as a Guide... but it should be a decent resource anyway.

As a starting point, I’ll take a look at the Vertex magneto. The Vertex originally started out made by Scintilla, a Swiss company in 1917. Scintilla had a number of divisions – for example it appears that it’s power tool division now belongs to Bosch.

On the magneto side, the aviation maggie business appears to be separate from the automotive maggie business. In 1921 Laurence Wilder obtained the American agency and brought the Scintilla aviation magneto to the US. By 1924 the Scintilla Magneto Company, a Swiss firm with headquarters in New York City, had a combination assembly plant and sales office in New York City and began manufacturing aviation magnetos in Sidney (no, not Sydney ). In 1929 the Bendix Aviation Corporation purchased Scintilla adding this Division to their group operations. During the WWII years alone Scintilla produced around 150,000 magnetos for military aircraft, tanks and boats along with ignition switches, ignition harnesses, distributor heads, spark plugs, fuel injection and spare parts. In 1982 Bendix merged with Allied Corporation, who sold the company to LPL in 1987. The company became Amphenol Aerospace Corporation and builds special connectors for military and aerospace markets. Note that the aviation maggies are big bulky units, very different from the Vertex maggies used on grey motors.

The Vertex automotive magneto part of the Scintilla business appears to have been sold differently. The table below (which I have summarised from The Rodders Journal #35 and #54) gives the history of the Vertex part of Scintilla’s business, along with means to identify the different Vertex variants.



Examples of the various caps and tags are shown below:




Advertisements for the various incarnations of the Vertex are shown below:



Many of the grey motor Vertex magnetos that are for sale on eBay and at swap meets are likely to be imports from America, bearing tags similar to the above and with the drive modified to suit the grey. However, GMH offered a magneto as an option on the grey motor industrial engine (as option 391). GM maggies have a Scintilla tag. The GMH magneto was often used where the industrial engine would not have any electrical system – the battery was deleted, the starter replaced by a hand crank, the distributor system replaced by the maggie, and the electrical gauges for oil pressure and water temperature replaced with mechanical units. The grey motor maggie was a Scintilla Vertex unit, and is described really well in the National Automotive Service Company Holden Industrial Engine Parts Catalogue M33146 (1961). The diagram and parts tables below come from that source (note that I'll append the diagram and table as a separate post... I can't seem to attach it to this post).

Vertex magnetos have an identification tag which gives timing information. For example, the tag may be stamped 600-2100-14. This would mean that the magneto has 14º of mechanical advance between 600rpm and 2100rpm. Note however that both speed and degrees of advance are stated in terms of magneto speed and magneto degrees, not crankshaft speed and crankshaft rotation. The numbers that we are used to dealing with when we set ignition timing are crankshaft speed and crankshaft degrees. Both of the figures stamped on the magneto tag must be doubled in order to determine crankshaft speed and degrees of advance. In our example above, the maggie will give 28º of mechanical advance between 1200 and 4200rpm. As a comparison, our standard grey motor distributor gives 30º of mechanical advance between 600 and 3450rpm (if Scintilla was putting an imaginary tag on a grey motor dizzy, it would read 300-1725-15).

The cap of Vertex magnetos have wire position numbers (1, 2, 3, 4, 5, 6) labelled with white stickers. From the factory, the numbers indicate the sequence of firing of the magneto i.e. spark will flow from the wire labelled as #1 first, then #2, then #3 etc. This magneto firing order should not be interpreted as the firing order of the engine (for our grey motor 1, 5, 3, 6, 2, 4). To work out what magneto wire to connect to which spark plug, a table is drawn up, with the top row being the numbers from the magneto, and the bottom row the firing order. For our grey motor:



This means we connect the magneto cable labelled 1 to spark plug 1, magneto cable 4 to spark plug 6 etc. The original Scintilla document describing this process is shown below:



Notwithstanding the above, be sure to examine the magneto cap closely. Many Vertex magnetos have undergone overhaul, with the stickers available as reproductions. Looking at some photos of freshly overhauled grey motor maggies, it appears that the stickers have been put onto the magneto in the engine firing order rather than the magneto firing order. Caveat emptor.

Pictured below is my Scintilla Vertex. It’s a pre-1978 unit made in Switzerland, which has been later modified by Joe Hunt Magneto. The maggie was run by Dud Lambert, a South Australian speedcar driver in one of his Holdens back in the 1960s. It runs fixed timing – the mechanical advance unit has been removed and replaced with a factory Scintilla locking set. The cap has been mislabelled with the engine firing order rather than the magneto firing order.









As a closeout to this post, I’d like to present the Scintilla Shuffle (with thanks to I. Jeremiah Palmer for bringing this to light). The Scintilla Shuffle is like the Curley Shuffle, made famous by Curley of the Three Stooges. To do the Scintilla Shuffle, hold one of the maggie high tension leads in one hand. With the other hand quickly spin the drive shaft. The dance created is called the Scintilla Shuffle. For those of you with fathers like mine that thought it hilarious to have their kids hold a live V8 plug lead, you probably already know the steps.

Cheers,
Harv (deputy apprentice sparkplug tester, nyuk nyuk nyuk).

[Harv]

Ladies and gents,

Attached information drawn from the National Automotive Service Company Holden Industrial Engine Parts Catalogue M33146 (1961) as promised:

magneto.docx

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Note that GMH owns the copyright on the original M33146 document. I've summarised that information in the attachment, expanding on the information in the original and only including the information relevant to this research (ie avoided scanning and appending the lot). If anyone believes the attachment breaches copyright, please let me know and I will remove it.

If anyone has an original GMH maggie, I'd love to see some photos.

Cheers,
Harv (deputy apprentice sparkplug tester)

[Harv]

Ladies and gents,

Another (relatively) common maggie for the grey is the Wico. Wico is the company name for the Witherbee Igniter Company, located in Springfield, Massachusetts USA. Wico originally manufactured electrical components for agricultural machinery from 1892, and later became the Wico Electric Company, manufacturing automotive igniters in the early 1900s. In 1926 the Wico Electric Company started a servicing depot in London, which developed into a magneto manufacturing factory and in 1941 this division was purchased from the American owners by the Ministry of Aircraft production. In the late 1940s Wico was merged with the British spark plug manufacturer Pacy to become the Wico-Pacy Sales Corporation (or Wipac), based in Bletchley, UK. Wipac manufactured a large range of mechanical and electrical products. In 1998 Wipac was purchased by Carclo, and continues to be an automotive supplier, specialising in prestige vehicle lighting.

Wico primarily made ignition systems for stationary engines. Early models (for single and twin cylinder engines) included models like the "L", "O", "R", “B1” and “B2”. By the late teens, Wico was producing maggies for a broader range of engine sizes, including the AX, PR (later replaced by the EK around 1919 – over one million EK magnetos were sold for single cylinder farm engines) and the OC models. Wico produced a very long line of rotary mags including the "LD", "A series", "C" (around 1939), and finally the "X series" (1946). The rotary mags were popular on John Deere and Case tractors, and countless other engines. Wico also made the J and JEM vertical rotary mags commonly used as an aftermarket option on &*#@ Model A cars.

Whilst there was no Wico factory magneto for the Holden grey motor (or at least none that I am aware of), it is possible to modify a Wico to suit a grey. Most of the grey motor Wico maggies I have seen are the model XV-6. The Wico X model magneto was available as both the XH (horizontal) and XV (vertical), with the XV-6 (6-cylinder model) used on grey motors. XV-6 models were available both with fixed timing and with mechanical advance.

The Wico X used an AlNiCo (aluminium, nickel and cobalt) rotor, which produced a better spark than the nipermag (iron, nickel, aluminium and titanium) material used on the Model C. The Wico X also had an improved bearing design, with the bearing on the outboard end of the rotor. However, there are some areas where some diligence is required on the Wico X:
a) the rotor button has a tendency to come loose, and may require the spring to be replaced.
b) the coil clamps crack and break over time, and can put debris into the rotor. These must be checked, and cracked units replaced.
c) The bearing is susceptible to rust and dirt, and can become sticky. If the rotor spins freely (except for two points of resistance per revolution), the bearing is acceptable. Sticky bearings require disassembly and replacement (this is a very common 6201 bearing).
d) Condensors should be checked - the condenser stamped X5700C should have a capacitance of 0.30–0.34µF, whilst the taped coil should have 0.16–0.20µF. Your typical grey motor automotive ignition coil condenser is 0.18-0.22µF.
e) Coil resistance should be checked, with the primary being 0.50Ω and the secondary 7500Ω.
f) Point opening should be ~0.015”, or slightly under.

Attached below are the Wico XV service parts list and brief instructions:

Wico XV service parts list and brief instructions.pdf

(5.12 MiB) Downloaded 311 times

The maggie shown below is a WICO XV-6, modified to suit a grey motor:











Cheers,
Harv (deputy apprentice sparkplug tester)

[Harv]

Ladies and Gents,

Attached below is the text of an article presented in Hot Rod magazine, December 1959 in blue font. It covers the Vertex magneto, and specifically Joe Hunt’s modifications to them. Joe was regarded as one of the top Vertex magneto authorities, a status his company keeps today. Note that the timing of the article was the hey-day of grey motor go-fast gear. This makes some of Joe’s comments interesting:

“Joe says that a good battery ignition system that has a distributor equal in quality and workmanship to a Vertex and has the correct advance curve will fire an engine's cylinders as well as a Vertex, as long as it is in first-class condition. A distinct advantage a Vertex has is that it is a completely self-contained ignition system.

Manufacturers of special battery ignition distributors have one selling point to prove their products can do a better job than a magneto in a competition engine. This is that their distributors, when used with suitable ignition coils, can create much longer and fatter secondary discharges than a Vertex, and that the discharges will jump the gap in a spark plug subjected to compression pressures much higher than the discharges from a Vertex can overcome. These claims are 100 percent correct.”

Today’s high-tech electronic ignitions (probably) outperform the old maggie… but interesting none-the-less that period “special battery ignition distributors” (like twin-point dizzies) were probably just as good as a maggie.


Don Francisco explores the ignition used on many a winning car – THE VERTEX MAGNETO
An ignition system for any type of spark-ignited internal combustion engine has one basic job and that is to create an electrical discharge at the engine's spark plugs that will ignite the compressed fuel and air mixture in the engine’s cylinders. Without these discharges an engine is nothing but a useless mass of iron, steel, and aluminum.
Any ignition system, ranging from those that are standard equipment on stock engines to the very best of the special ones, is equal to the job of creating electrical discharges at a stock engine's spark plugs. But an engine that has been modified for competition increases the load on its ignition system, and it must use the fuel and air mixture that is compressed in its cylinders to the very best advantage. This means that the mixture must not only be ignited, but also that it must be ignited at exactly the correct time, as determined by the positions of the pistons in their cylinders.
The reason the mixture must be ignited at the correct time for each power stroke is that the time of ignition has an effect on combustion pressure, which is the pressure created in the cylinders by the burning mixture. An engine’s power output is dependent on combustion pressure; the higher the pressure, the greater the output. However, the maximum combustion pressure an engine that has good breathing characteristics and a high compression ratio can use is determined by detonation. When detonation occurs, power drops off and more than likely the engine will suffer mechanical damage.
The direct cause of detonation is heat. During normal combustion a flame front that originates at the spark plug moves across the combustion chamber, consuming the unburned mixture as it moves. The mixture expands as it burns and this expansion further compresses the unburned mixture. One of the laws of physics is that the temperature of a gas is raised when the gas is compressed: therefore. as the unburned mixture is compressed by the flame front, its temperature rises. Heat from the flame front boosts the mixture's temperature even higher. Temperature increases from these sources don't create any trouble because the mixture dissipates most of its heat to the combustion chamber surfaces.
The deviation from the normal combustion process that causes an engine to detonate is that the unburned mixture doesn't dissipate heat to the combustion chamber surfaces fast enough as it is compressed and heated by the flame front. The result is that its temperature rises to the point where it ignites spontaneously. This is often referred to as "autoignition.'' Ignition of the unburned mixture in this manner creates an abrupt pressure rise in the chamber that upsets the normal combustion process and causes the sound generally described as "ping."
Detonation can be eliminated by several methods. This includes lowering the compression ratio, redesigning the combustion chamber, installing a camshaft that closes the intake valves later, using a better grade of fuel, richening the fuel mixture for full-throttle operation, firing the mixture later, etc.
An engine's compression ratio can be lowered by increasing the capacity of its combustion chambers. This is done by reworking the cylinder heads, installing different heads, installing different pistons or by combinations of these things. A camshaft that closes the intake valves later reduces the quantity of mixture in the cylinders at the beginning of compression strokes. This has the same effect as lowering the compression ratio. The best possible fuel should be used in a competition engine as a matter of course, as should rich fuel mixtures for full-throttle, maximum power conditions. This leaves ignition timing as the only truly adjustable effect on detonation. The timing must be such that combustion pressures in the cylinders will be as high as they possibly can without causing detonation. To achieve this, the mixture must be fired at the correct time at all crankshaft speeds. Any other condition will cause a loss of power.
Because the mixture burns slowly during normal combustion, it must be ignited early when an engine is running at high crankshaft speeds so that combustion pressure will be at its maximum value when the piston starts down the cylinder on its power stroke. This means that ignition must take place before the piston has reached its top center position in the cylinder on its compression stroke.
If ignition occurs before it should, too much of the mixture will have been ignited and expanded by the time the piston reaches top center. This will cause the unburned portion of the mixture to be compressed rapidly to such a high pressure that detonation will occur. If the time of ignition is later than it should be, too little of the mixture will have been burned and expanded by the time the piston reaches top center and the pressure to force the piston down the cylinder will not be as great as it should. The number of degrees of crankshaft rotation where ignition should occur at high crank speeds varies in competition engines but it is usually between 25 and 40 degrees.
Another thing about ignition timing that must be considered is that automobile engines that are modified for competition use have more than one cylinder. As far as their normal functions are concerned, each of the cylinders must be treated as an individual single-cylinder powerplant. If the engine was reworked correctly and assembled properly, the functions of the parts in each of its cylinders will be identical, therefore, the ignition timing for all the cylinders must also be identical.
The heart of a battery ignition system is its distributor. Unfortunately, distributors supplied as standard equipment on automobile engines have neither the design nor the quality to make them suitable for competition engines. This leaves an unfilled opening in the cylinder block of a converted engine into which a special distributor or a magneto must be inserted before the engine will perform as it should. In 90 percent of the really hot competition engines in hot rod ranks, and in nearly all of the engines used in professional racing equipment this opening is filled with a magneto. The disadvantage of a battery ignition system for a race car is that it requires a battery. Batteries are heavy and one could shake apart on a rough track.
Several makes of magnetos are available for modified automobile engines but the one that is the most popular, almost to the exclusion of the others, is the Scintilla Vertex. A product of Scintilla Ltd., Soleure, Switzerland. Vertex mags were once standard equipment on many of the higher-priced automobiles of foreign manufacture. Now, in this age when the dollar, pound sterling, franc, lira, and mark are more important than quality to automobile manufacturers, they are reduced to the role of replacement equipment available to anyone but used in volume only by owners of engines that must have a high quality, dependable ignition system.
Vertex mags are distributed in the western portion of the United States by a man named Joe Hunt. Joe's name is familiar to every serious hot rodder and every professional race car mechanic in the country. This recognition is the result of fourteen years in the magneto business during which Joe's company has provided mags for every conceivable type of hot rod, race car, motorcycle, passenger car, and anything else that is driven by a spark-ignited internal combustion engine. Joe is the man to talk with about problems involving magnetos and ignition systems in general.
Joe says that a good battery ignition system that has a distributor equal in quality and workmanship to a Vertex and has the correct advance curve will fire an engine's cylinders as well as a Vertex, as long as it is in first-class condition. A distinct advantage a Vertex has is that it is a completely self-contained ignition system.
Manufacturers of special battery ignition distributors have one selling point to prove their products can do a better job than a magneto in a competition engine. This is that their distributors, when used with suitable ignition coils, can create much longer and fatter secondary discharges than a Vertex, and that the discharges will jump the gap in a spark plug subjected to compression pressures much higher than the discharges from a Vertex can overcome. These claims are 100 percent correct.
One thing few persons realize about ignition systems is that they create only enough secondary voltage to overcome the resistance between a spark plugs electrodes. This resistance is determined primarily by the pressure in the cylinder and the distance between the electrodes. If it is low, such as when the engine is running under light load, the voltage will be low. If it is high, such as when the engine is running with full-throttle at moderate engine speeds, the voltage will automatically rise to the value required to bridge the gaps. An ignition system fails to fire its plugs when the voltage requirement at the plugs becomes greater than the voltage it can create.
Compression pressure in the cylinders of a given engine may reach a maximum of 250 psi or more when measured with a compression gauge but this isn’t the pressure that exists between the spark plug electrodes when the mixture is ignited. Compression pressure measured with a gauge is at its maximum when the piston is at top center at the end of the compression stroke. Pressures before top
center are considerably lower, and as explained previously, the mixture in the cylinders of an engine that is running at cruising or high speeds is ignited several crankshaft degrees before the pistons reach top center.
The only times the mixture is ignited at or near the end of the compression stroke is when the engine is idling or running at very slow speeds with closed or nearly closed throttle. Under these conditions pressures in the cylinders are low because the closed throttle does not allow the cylinders to induct enough fresh mixture to create high pressures. Voltage requirements at the plugs are at their lowest at these times.
Exceptionally fat and long sparks, can be of value when there isn’t sufficient fuel in the compressed mixture for the volume of air, or the fuel and air aren't mixed properly. An ignition system can't be considered deficient if it won’t fire such mixtures. The fault lies with the carburetion system or in the design of the engine's combustion chambers. An engine with such faults will not succeed in competition because it will not be able to deliver the horsepower it should.
Something else that should be understood about the discharges that occur between a spark plug's electrodes is that the first spark is the only one that counts as far as ignition of the mixture is concerned. All conventional battery ignition systems and magnetos create more than one spark at a plug each time their breaker points open. This is the result of the normal flow of current in their circuits. The only effect second and subsequent discharges for each power stroke have is to cause excessive erosion, or wear of the plug's electrodes.
One feature of a mag about which there is little argument is its ability to create secondary discharges of adequate voltage at high engine speeds. This characteristic is due to the fact that the voltage of the
primary current created by a mag continues to rise as the speed of rotation of its drive shaft is increased. This is the reason it is possible for a Vertex to function efficiently at high crankshaft speeds although it has only one set of breaker points and only one coil.
During discussions about magnetos someone always makes the statement that an engine fitted with one of them is hard to start. This may have been true years ago with some mags, and perhaps it applies even now to mags of some makes, but it doesn't apply to a Vertex. A magneto's ability to create primary current for its coil is dependent on the speed of rotation of its driven shaft. In a Vertex the speed of shaft rotation at normal engine cranking speeds is quite a bit faster than that required to create secondary discharges. The feature of the Vertex that makes this possible is the large diameter of its magnet assembly. This large diameter causes the speed at which the outer circumference of the rotating portion of the assembly moves in relation to the stationary portion to be considerably higher than necessary.
The choice between a Vertex and a special battery ignition system, as Joe explains it, cannot be based entirely on the ability of either to fire an engine's spark plugs. This question has been proven for both systems by actual experience with hundreds of applications. The deciding factors are the quality of the systems, their ability to function accurately for long periods of time, and possibly the problem of weight. In these things, he says, the Vertex definitely scores high. This is due not only to things that can be seen and measured but also to the principle on which a magneto operates. One important effect of this principle cannot be duplicated by a battery ignition system. It concerns the current in the magneto's primary circuit.
A Vertex mag, as do all magnetos, produces its own primary current. The mag's coil uses this current in a normal manner to create secondary discharges for the spark plugs. However, this current differs from the direct current used in battery ignition systems in that it is alternating current. This fact adds thousands of miles to the life of the contacts on a magneto's breaker points.
Direct current, such as that from an automobile's battery, always flows in the same direction. As it is characteristic of current flowing from one contact to another to cause minute particles of metal from one contact to be deposited on the other, one of the breaker point contacts in a battery ignition system will become pitted and small peaks will be built up on the other. Vertex point contacts aren't subjected to this carryover condition because the direction of the alternating current through them is constantly changing.
Because they are subjected only to alternating current, magneto contacts can be made of platinum instead of the tungsten that is used for the contacts in most battery ignition systems. Platinum is expensive but it has very good electrical conductivity properties. Contacts made from it also have the advantage of high resistance to burning that might be caused by foreign matter that collects on contacts during normal ignition system operation. The advantages of platinum contacts cannot be applied to battery ignition systems because platinum is more susceptible than tungsten to metal carryover caused by direct current. Joe says it isn't at all uncommon for Vertex points to give a hundred thousand miles of service.
Another good feature of Vertex points is that the design of their movable arm and the spring that moves the arm to close the contacts allows them to operate efficiently at engine speeds in excess of 8000 rpm. Joe sometimes recontours the spring, and in some units he uses two springs to obtain the desired pressure. However, the pressure is never made so high that it will cause the arm to bounce when the contacts close. Excessive pressure can also have a reverse effect on the arm that will tend to cause the arm's rubbing block to leave the cam at high rpm.
Correct alignment of the contacts is guaranteed by locating the movable point arm on its pivot pin with a circular clip. The arm cannot move up and down on the pin and throw the contacts out of alignment. Once the points have been adjusted correctly, their positive alignment, extremely low rate of contact wear and wide, slow-wearing rubbing block allows them to remain in adjustment for thousands of miles of operation.
Vertex breaker cams are precision ground to a concentricity that has a total runout of not over .0005-inch (one-half thousandth-inch). Great care is taken to space their lobes equally so that the lobes will fire each of the cylinders at exactly the correct times in relation to crankshaft position. This is extremely important if each of the cylinders is to develop its maximum power potential. Correct alignment of the cam with the points is guaranteed by supporting the upper end of its shaft with a ball bearing. Maximum support is obtained from the bearing by placing it only .010-inch below the cam. A recess in the point plate, which is rigidly mounted in a recess in the mag housing, locates the bearing. The lower end of the shaft is located by the mag's drive shaft.
Magnets in the section of the magneto that creates primary current are made of Alnico. This is an alloy of aluminium, nickel and cobalt. For many years it has been the best commercially available permanent magnet material. The number of poles and pole shoes in the magnet setup is equal to the number of cylinders the magneto serves. This is necessary in a mag that runs at one-half engine speed, as does the Vertex. The rotating portion of the assembly is attached to the lower end of the shaft that drives the breaker cam.
The coil that transforms the primary voltage to secondary voltage is a heavy duty mica insulated unit. It is inside the magneto's housing where it is protected from moisture and mechanical damage. A high-quality condenser is secured to the breaker point plate with a sturdy bracket. It has a stud connector for the lead to the points which enables it to be sealed efficiently against moisture. It has the correct capacity for the coil, which is essential for any condensor if it is to fulfil its duty of minimizing arcing across the breaker points.
The cap and its rotor are well designed. Segments in the cap that receive voltage from the rotor are a full inch apart to minimize arcing, or flashover, between them. Arcing between cap contacts or between the rotor and the wrong contact is one of the things that can limit the usefulness of an ignition. Arcing of this type occurs when the resistance at a spark plug's gap when the gap is under compression becomes greater than the resistance between the contacts or between the rotor and a wrong contact. Cables for the spark plugs are anchored in the cap by pointed screws that pass through the sides of their insulator and conductor.
Accurate control of the ignition advance curve provided by a Vertex is assured by several governor plates that vary in weight and the way they are shaped to limit their control over the curve. Centrifugal force acts on these plates as they are rotated with the magneto’s drive shaft. As the speed of rotation increases, the force on the plates becomes greater and moves them farther from the axis of rotation. This movement causes the magneto to fire the spark plugs earlier in relation to crankshaft position. The rate and amount of advance is adjusted to any specification by using the plates in different combinations.
Correct adjustment of the advance mechanism is so important to engine performance that Joe will not sell a Vertex for competition use unless he is allowed to tailor its advance curve to match the engine's requirements. Before he can do this he must have the following information about- the engine: make, year, and number of cylinders; bore, stroke and compression ratio; camshaft grind that will be used; fuel that will be used; carburetion system, including the make and number of carburetors or the type of injector setup and, if the engine is blown, information about the blower; the type of chassis, hull, or whatever the engine is to be used in; the weight of the complete car, boat, or other; and the type of competition for which the engine will be used. Experience gained over the years makes it possible for Joe to determine from this information the exact advance curve that will enable the engine to develop the highest possible combustion pressures without detonating.
Vertex mags aren't restricted to competition engines. Their adjustable advance curve, quality materials, and correct firing intervals between cylinders also make them adaptable to passenger car engines. Their dependability is the reason they are used in many engines that must run continuously, day in and day out, such as those that drive pumping rigs for oil and water wells.
As Joe receives them, Vertex mags have a short, small-diameter base designed to fit engines of European manufacture. Recently an optional base fitted with an integral tachometer drive was also made available. Before a Vertex can be used in an automobile engine manufactured in the United States, it must be fitted with a special base adaptor to match the engine. Joe makes these adaptors and presses them onto the original base. Bronze bushings in the adaptors support the shaft that drives the mag.
Installation and timing of a Vertex follows essentially the same procedure required by a battery ignition distributor. Cable sockets in a Vertex's cap are numbered according to the order in which they receive current from the rotor, not according to the engine's firing order. To determine which cable goes into which socket, write the numbers 1 through 8 on a piece of paper and then write the firing order of the engine under these numbers so that the 1 in the firing order is under the 1 in the upper row of numbers. The cable for each cap socket is the one for the cylinder whose number is below the socket's number.
Under no circumstances should standard TVRS spark plug cables be used with a magneto or any other special ignition system. This cable can be identified by its carbon-coated conductor. Joe recommends Packard 440 cable because of its high quality. He also recommends Rajah crimp-type terminals for the plug ends of the cables. Rajah makes the popular solderless two-piece terminals in which the parts are joined by threads but these sometimes separate when the engine is running and cause the loss of the cylinder. This could mean a lost race. When using crimp-type terminals, be sure to solder the conductor in each cable to some portion of its terminal to guarantee a positive electrical connection between the two.
Plug cables in the groups that serve the banks of a V8 engine should be separated rather than grouped together. The reason for this is that a high voltage flowing through one cable can induce a high voltage in another cable that is close to it for any appreciable distance. This induced voltage in the second cable will fire the spark plug the cable serves. At some points in a cylinder's four cycles this wouldn't cause any harm but if there were fresh fuel and air mixture in the cylinder, the mixture could be fired prematurely. This could result in severe detonation and damage to the engine. This condition is called "cross-firing." It is a common problem with some makes of engines if the plug cables aren't separated by correct routing.
&*#@ makes a rubber separator for plug cables that is ideal for any installation. Its part number is FAA-12297-C. These separators accommodate four cables but they can be cut in two for two cables. A piece of tape wrapped around a separator after the cables have been inserted in it finishes the installation. At least two separators, one for four cables and the other for two cables, should be used for each cylinder bank on V8 engines.
Special ignition switches are made for magneto installations but for competition use an ordinary toggle switch will do the job. Connect the lead from the magneto's primary post to one side of the switch and another wire from the other side of the switch to any grounded surface. The mag will operate when the switch is in its normal "OFF" position. A toggle switch or a special key-type switch can be used in a passenger car.
Don't connect the lead from the mag’s primary post to the distributor terminal of a standard ignition switch. If this is done, current from the car’s battery will flow into the magneto when the switch is in its "ON" position. This will cause serious damage to the mag. It is possible to use a standard ignition switch by installing a special relay between it and the mag. Current from the battery operates the relay and the relay makes or breaks the circuit between the mag and ground.
A Vertex mag is not the least expensive ignition system one can buy. Models range in price from $105 for those for four cylinder engines to $165 for eight-cylinder tach-drive models. Facts that must be considered are that a Vertex can be easily switched from one make of engine to another because it can be converted at little cost for installation in any engine that has the same number of cylinders for which it is designed, and that, due to its excellent construction and reputation for long life, it will have a high resale value for many years. It isn’t at all unusual for a used eight-cylinder Vertex to sell for as much as $125. This is a goodly percentage of its original cost.

Cheers,
Harv (deputy apprentice sparkplug tester)

[GreyEJ]

Top reading Harv. Also being the proud owner of a Vertex Mag this is very interesting. Replacement parts can be sourced from:

Hardiman Auto Supplies Pty Ltd
Redline Performance Pty Ltd
Ph: 02 8723 8888
Fax: 02 9771 2176
Sales@redlineauto.com.au

Keen to read more.

[Harv]

You want more? OK, I gots some more

For the post below, I’m going to delve into the details of the Vertex magneto, mainly as an excuse to post up a photo of a cool grey motor maggie. A word of warning: Zim Pirates who love their doof-doof music without the scream of magneto interference should not read the information below.

To maximise the grunt delivered by the magneto, it is normally recommended that radio suppression spark plug leads are not fitted, and instead that stainless wire core leads are used. For the same reason, non-resistor plugs are recommended for use in maggies, though should not be a drama as the “standard” spark plugs for the grey motor are non-resistor (you normally see resistor plugs in Zim Pirate modern on-board computerised cars). The upshot of this is that a normal maggie will put out a fair amount of radio interference – enough to make AM radio distorted, and in some cases give good scatter on your neighbours television.

Scintilla recognised that not everyone chooses the “radio delete” option when running their vehicle, and offered two types of radio interference suppression for the Vertex:
a) Distant interference suppression. To correct this, the magneto distributor rotor was replaced by one with 5000Ω resistance (part number 1643), and resistance-type plugs (or plug connectors with built-in resistance) used, with the total resistance per ignition circuit not exceeding 10,000 Ω.
b) Close interference suppression. In this case the magneto was screened with a special metal hood and screened (braided) spark plug leads. This was referred to as “radio screening type LRO”, and is shown in the diagram below:



1. Screening hood
2. Distributor head
3. Vertex housing
4. Fastening screw
5. Spring ring
6. Connection sleeve
7. Ignition lead
8. Clamp
9. Pointed screw
10. Insulating nut (for standard design of Vertex)
11. Primary connection screw
12. Insulating washer
13. Insulating washer
14. Washer
15. Flat nut
16. Washer
17. Spring washer
18. Flat nut
19. Threaded sleeve
20. Connection sleeve
21. Screw cap

To fit the radio screening type LRO:
a) Every spark plug lead must be screened, using high voltage leads with metal braid. Remove the braid from the end of the lead for a distance of about 1", taking care not to damage the insulation.
b) Slide the gland nut (item 215 in the drawing below) and large sleeve (item 214) over the metal braid. Slightly form the braid outward.

c) Push the small sleeve (item 213) under the braid so the braid is gripped between the two sleeves.
d) Push the rubber seal (item 212) over the lead end from which the braid had been removed.
e) Terminate the leads with a metal sleeve and solder connection.
f) Insert the prepared lead into the screened distributor head and fasten with a nut (item 215).
g) Repeat for the other five spark plug leads.
h) Detach the Vertex head (2) from the housing.
i) Unscrew the insulating nut (10) of the primary connection and replace the unscreened primary lead with a screened one.
j) Remove items (13) to (18) as well as the existing primary connection screws.
k) Insert the large insulating washer (12) into the threaded sleeve (19) and secure both parts with the new primary connection screws (11).
l) Fasten the previously dismantled items (13 to 18) to the Vertex.
m) Insert the new screened primary connection lead into the connection sleeve at the Vertex with the screw cap (21).
n) Fit the screening hood (1) onto the head (2), then insert the separate ignition leads (7) and secure them with pointed screws (9). Make sure that the pointed screws really penetrate the leads and that there is good contact.
o) Pull the metal braiding over the sleeve (6) and secure with the clamp (8).
p) Insert the spring ring (5) in the groove of the screening hood. Its purpose is to prevent the head (2) from falling out, and at the same time to provide a metallic seal between the screening hood (1) and housing (3).
q) Attach the assembled distributor head to the housing with screws (4).


OK, OK I hear you… enough theory, more pictures. The picture below shows a grey motor Scintilla Vertex maggie (potentially one of the GMH ones) with the radio screening hood.

Interesting that the tag shows 300-1250-11 – 22º of mechanical advance starting at 600rpm, all-in at 2500rpm. It’s a little low for a naturally aspirated grey (28-32º all-in at 3450rpm), but absolutely perfect for a supercharged one.

The pictures below show an assembled hood on an eight cylinder maggie:






P.S. You wanna post photos of your Vertex Paul, or want me to?

Cheers,
Harv (deputy apprentice sparkplug tester).

[Harv]

Ladies and gentlemen,

Having had a look at grey motor maggies from Vertex and Wico, this post is going to focus on something different – Bosch magnetos (yep, another excuse to post a photo of a grey motor maggie ).

Bosch has been manufacturing magnetos since 1898 (their first maggie was installed into a Dion Bouton three-wheeler, and needed 900 sparks/minute… the magneto could only supply 200). Bosch supplied the magneto for the first Zeppelin (LZ1) in 1900. By 1901, Bosch had made significant improvements to the magneto, and by 1902 launched the first commercial spark plug. By 1906 Bosch had an active sales unit in the US, which was to become the Bosch Magneto Company. US manufacturing commenced in 1908, and flourished. Prior to WW1, nearly 90% of Bosch’s global sales were in the US. Bosch’s American assets were seized in 1918, with the company later becoming the American Bosch Magneto Company. The German parent company continued to operate, though magnetos continued to be expensive. By 1930 a magneto represented 10% of the total vehicle cost, and only one third of German vehicles still used them over battery ignition. The two Bosch companies merged to form United American Bosch Corporation, based in the US. This organization was known simply as American Bosch Corporation from 1938. During WW2 the company was again seized by the U.S. government. By 1942 Bosch magnetos or fuel injectors appeared in virtually every U.S.-built plane, battleship, aircraft carrier, destroyer and submarine. In 1983 the Bosch Group won back the trademark rights expropriated during the war and finally regained the unrestricted right to use the Bosch name worldwide.

Bosch made the following magnetos up to at least 1938 (I don’t have any info to hand later than that):
AR1 Niedorsp (1907-1911)
AR2 Niedorsp (1901-1923)
AR3 Niedorsp (1904-1920)
AR4 Niedorsp (1901-1920)
ARH Niedorsp (1900-1925)
ARN Niedorsp (1901-1924)
D2 (1905-1920)
D2R) (1905-1916)
D3 (1905-1920)
D3R (1906-1916)
D4 (1905-1920)
D6 (1905-1920)
DA (1910-1915)
DAg (1906-1919)
DA Gnome (1910-1919)
DA1 (1906-1922)
DA1 2Zyl (1907-1916)
DA1v (1907-1920)
DA2 (1903-1922)
DA2 2Zyl (1905-1914)
DA2v (1905-1906)
DAFN (1910-1912)
DAM (1906-1912)
DAV (1906-1920)
DF2 (1910-1920)
DF4 (1909-1920)
DF4v (1911-1920)
DF6 (1910-1921)
DO1 (1909-1920)
DO2 (1907-1920)
DO4 (1909-1916)
DR3 (1907-1913)
DR4 (1906-1920)
DR6 (1907-1920)
DU (1910-1916)
DU1 (1908-1920)
DU3 (1909-1917)
DU4 (1908-1920)
DU5 (1910-1920)
DU6 (1910-1916)
DUv (1908-1920)
HD2 (1908-1917)
HD4 (1908-1919)
HDh (1902-1920)
HL6 (1910-1928)
HL8 (1909-1928)
K4 Magnetker (1907-1915)
K6 zenzunder (1907-1920)
Z4 (1912-1935)
Z6 (1912-1932)
ZA1 (1911-1931)
ZA1 FN (1911-1923)
ZA 4 (1912-1930)
ZAV (1911-1929)
ZE1 (1911-1930)
ZE2 (1911-1932)
ZEV (1911-1928)
ZF4 (1911-1934)
ZF6 (1911-1931)
ZFN (1911-1912)
ZFN4 (1912-1922)
ZH4 (1910-1924)
ZH6 (1912-1935)
ZR4 (1910-1938)
ZR6 (1911-1934)
ZU (1912-1934)
ZU1 (1912 – 1938)
ZU2 (1911 -1938)
ZU4 (1911 -1936)

Just like the WICO, I do not believe that a Bosch magneto was made for the grey motor though some were adapted to suit. The photos below show a Bosch maggie modified to suit the grey motor:





I don’t have any detail on the model number for this one, or whether it is a German Bosch or American. If you own it, I’d love to hear from you.

Cheers,
Harv (deputy apprentice sparkplug tester)

[Harv]

Ladies and gents,

Attached below the text from an article published in Custom Rodder October 1962 Volume 11 Number 4. The article compares the advantages and disadvantages of maggies and dual-point dizzies.

THE HOT IGNITION systems available to hot rodders today consist of dual point conversion kits, hot coils, dual coil setups and last but not least, the magneto. Installing dual breaker points and a hot coil is a fine addition to a stock or mildly reworked mill. However, for maximum output on a hot super stocker or an all-out competition car the only choices are the magnetos or the dual coil distributors. With Detroit raising the cubic inches, horsepower and compression ratios each year, the demands of the electrical output of the stock ignition systems is also greater. Many of the hot Detroit mills need more efficient ignition systems than they are equipped with, but the high cost is prohibitive. Both the dual coil and magneto systems have advantages and disadvantages. However, your the one who must make the decision, if you want a top machine.

Points to think about are initial cost, maintenance, ease of installation and long term cost. This article can not make up your mind for you but it does describe and evaluate the fine points and principles of both systems and it points out their advantages and disadvantages.

Thanks to the crew at Strick's Speed Shop, 1816 14th St. N.W., Washington D. C., we were able to take photos of the different systems inside this article. Remember don't neglect the ignition end of a hot mill, unless you want to be known as "an also ran."

One of the most popular magnetos used by rodders is the Scintilla Vertex magneto manufactured in Soleure, Switzerland and reworked in the United States, by Joe Hunt in California and Ronco in Pennsylvania. This magneto can be used on a large variety of mills by simply changing the shaft and gears to match the setup used on the stock distributor.

The Vertex has a fully adjustable weight advance mechanism which allows the mag's advance curve to be tailored to any mill. By simply adjusting the spring tension of the platinum-tipped points, they will operate efficiently at speeds of 8,000 plus rpm. Vertex magnetos range in price from 105 dollars to 165 dollars. Now lets get down to the basic principle of the magneto ignition system.

A magneto has the unique feature of generating higher voltage as the engine rpm's increase, the opposite of a stock ignition system. In other words, the voltage of the primary current for a magneto coil is at its lowest value at low rpm and at its highest value at high rpms. It's like having your cake and also eating it!

The use of different weights (plates) enables you to control the magneto's (Vertex) ignition advance curve . On a competition car the installation of a magneto such as the Vertex is a simple matter, however, a street car requires a little more wiring work. The magneto can operate without a battery, its source of electricity coming from within itself, rather than from an exterior source. Basically, it's a small electric generator which builds up a charge as the armature rotates through the permanent magnetic field.

The complete magneto ignition system is built into one compact case (except the Mallory Mini-Mag), containing the points, coil, -etc. Although compact, the Vertex magneto stands approximately 1½ inches higher than a stock distributor, sometimes causing a clearance problem when the car is running a Jimmy blower.

Most magneto systems are only available with a centrifugal advance mechanism, not offering some of the street advantages of vacuum and centrifugal advance. When a magneto is used in a street car utilizing a battery, a special relay must be used between the ignition switch and the magneto to correctly open and close the magneto's primary circuit. This is not necessary for a competition car.

Construction of the popular magneto systems such as the Vertex, Mallory, Harmon-Collins, is far superior to that of any stock ignition system, the only one coming close is the Spaulding Flamethrower discussed in the dual coil section. All in all the magneto system is just about the finest ignition setup available.

Dual coil systems on the market today are manufactured by Spaulding, Kong, Harmon - Collins and W&H. Prices range from 69 dollars for the W&H DuCoil to 108 dollars for the popular Spaulding Flamethrower, plus the cost of an additional one or two coils. To illustrate an example of a dual coil system we chose the Flamethrower unit, one of the finest around.

The Flamethrower is not a reworked stock distributor, it's a beautifully made unit very similar in appearance to that of a magneto. They are available without a vacuum advance for competition or with a combination vacuum governor weight advance assembly for any type driving.

Flamethrowers are also available with or without a tach drive for hooking up a mechanical tach. The governor advance assembly is located in the lower portion of the cylindrical aluminum housing which is finished with perfection. Each side of the distributor has a plastic terminal plate which allows access to the dual points and the four lobe cam.

When ordering a Flamethrower you must indicate the engine specs and equipment so that Spaulding can set the best advance curve. Now we'll get down to the fine points of a dual coil ignition system. The dual coil system features two coils, dual points and a four lobe cam; it is basically two complete four cylinder ignition systems, each operated by a common cam.

With this setup installed on your mill you are only opening the points half as many times per second as those of a stock eight lobe cam system. Thus, with a dual coil ignition there is less chance for the points to bounce and float, making high engine revs condenser and one coil take care of four cylinders, while the other set of points, condenser and coil take , care of the remaining four cylinders.

In this way, they divide the work between them, each carrying one half of the load of supplying the mill with the proper spark. With a dual coil, four lobe distributor, care must be taken to insure that the points are synchronized so they open at exact intervals of 45 degrees of cam rotation and provide the same dwell. Dual coil ignition systems are turning up on more and more competition and dual purpose care providing the fact that they are producing and have been accepted. The cost is not low but you cannot afford to neglect the ignition end of a hot mill. Dual Mallory or Detroit optional equipment coils are a good choice to use in conjunction with a dual coil setup.

Cheers,
Harv (deputy apprentice sparkplug tester)

[Harv]

Ladies and gents,

For those who have just bought an eBay Vertex (or have robbed a forklift/cement mixer/farm engine of its original GMH maggie), there are a few things that need to be done prior to bolting it down and firing up the grey. In some of the posts below, I will cover things to think about when installing your new magneto.
Magnetos are a self-contained ignition system – they don’t need external power to work, which is very different to the standard Holden ignition. In our factory early Holden, the engine is stopped by turning off power to the coil. With a magneto installed, this no longer works – turning off the ignition key will not stop the engine. This needs thinking about before the maggie is fired up… it’s not much fun having a running car you can’t easily stop.

Magnetos have an earth terminal (sometimes called a kill terminal) on their side. For the Vertex, the terminal may be marked “P”, and has a nice thumbscrew in the side of the casing. Do not ever, ever connect the kill terminal to +12V – you will cook the primary windings in the magneto. This terminal needs to be wired to an earth switch (I’ll call it a kill switch). To run the engine open the kill switch (stop earthing the magneto). To stop the engine, close the switch (earth the magneto). The simple kill switch wiring is shown in the image to the left below.



Whilst the use of a separate kill switch is cool in a race car, it can be a bit more painful in a daily driver – it would be nice if the existing key ignition switch did the job. You can use the existing Holden key ignition switch by installing a relay. Most relays we use in cars are used to switch +12V on and off. For the magneto, we will instead switch earth on and off. The wiring is pretty simple, and uses the existing power lead to the coil as per the image to the right above. When buying the magneto kill switch (or relay), it is a good idea to buy a decent quality component (eg NARVA). Many magneto rebuild shops indicate that when the magneto is running at full speed the primary windings (which the kill switch works on) can develop pretty high primary voltages. This means that the maggie can jump the contacts in the kill switch/relay, resulting in an ignition misfire. I’m a little bit dubious of this claim, as most of the test results I have seen for Vertex primary windings are of the order of 5A and 30V AC… not huge loads. Having said that, the cost of a decent switch/relay is pretty low compared to the cost of a grey motor maggie – cheap insurance.

As an aside, there are times when the separate (not ignition key) kill-switch is handy. If the magneto has fixed timing, it will generally have waaaaaay too much advance at startup compared to a “normal” engine. When cranking over the engine, the magneto may fire the charge early (especially if the engine is hot), making the piston push backwards. This can break teeth from the starter or ring gear. If your maggie has fixed timing, consider running the serate kill-switch inside the cabin. Turn the earth switch to closed (ignition off) until the motor is cranking over strongly (2-3 seconds) then flip the ignition system back on. This lets the engine build enough speed to overcome early firing, preventing it from spinning backwards.
So what does the kill switch actually do? To understand that, we need to look at some magneto theory. I’ve taken a presentation made at a Gathering of the Green (John Deere tractor enthusiast) meeting and modified it below – hopefully makes the maggie easier to understand.

The diagram below shows a simplified magneto, with each of the parts labelled:



This diagram does not have a kill-switch – we will add that later. Most of the parts in the diagram (except the sparkplug) are all internal to the Vertex magneto casing. The two magneto earth connections are made by the magneto body earthing through the engine block – there are no external earth leads. The sparkplug earth is similarly made by the sparkplug body earthing through the engine block. The pretty star in the rotor is only there so you can easily see how far the rotor turns in the diagram below.

As the rotor spins (clockwise in the diagram below), magnetic lines of force flow out of left end of the rotor (the rotors North pole), through the coil core, and back to right end of the rotor (the rotors South pole). This is shown by the blue arrows in the diagram below.



At this time the points are closed (they are shown on the left of the diagram). The spinning rotor causes less and less of the rotor to be covered by the laminated iron core. This makes the magnetic field through the coil decrease – the diagram below has less blue arrows. The changing magnetic field causes current to flow in the coil primary windings, as shown by the green arrows in the diagram below.



As rotor continues to spin, the current flowing in the primary windings will increase to a maximum value. This is a critical position where the magnetic field is collapsing and reversing in the coil. Opening the points at this rotor position (referred to as “Edge Gap”) produces the “best” spark. As the points begin to open, the primary resistance increases from ½Ω to infinity. The current in the primary windings drops to zero, and the voltage in the primary windings spikes. There is a potential for arc at the points as they open. To prevent this, the condenser begins to charge (as can be seen in the green lines flowing into the condenser in the diagram below), absorbing the current and reducing/eliminating the arc.



As the points continue to fully open, the potential for arc stops. The rotor position (north and south pole alignment relative to the laminated iron core) has changed. This causes the magnetic flow through the coil reverse. The condenser discharges back into coil primary windings. The reversal of magnetic field induces a high voltage in the coil secondary windings, as shown by the red arrows beginning to appear in the diagram below.



The high voltage in the coil secondary windings overcomes the plug gap resistance. The current flows in the secondary windings, jumping the spark plug gap as shown in the image below. We’ve got spark! (or, if you had the maggie in your hand, we have the Scintilla Shuffle).



The spinning rotor moves to be 180° from where we started – see the diagram below. The process begins again with the magnetic fields in the opposite direction. As the cycle runs through again, we get our second spark for the single rotor revolution. The cool thing here is that the reversed magnetic fields make the current flow the opposite way in the primary windings, and the arc tries to jump the other way cross the points. Arcing tends to deposit metal from one side of the points to the other, causing pitting. By making the current flow one way then the other (alternating current) across the points, the pitting tends to reverse itself. This is why magneto points last a lot longer than distributor points (distributor points have current running only one way as direct current, causing metal to transfer in one direction only).



So how does the magneto kill switch work? The kill switch is shown by the purple lines in the diagram below (the diagram shows the kill switch open, letting the magneto run).



Effectively, the kill switch provides a bypass around the points. When the switch is open, it does nothing (and the magneto runs). When it is closed, the switch makes the magneto think that the points are permanently shut. Current will still flow in the primary windings. What is missing though is the sudden change in magnetic field in the coil that occurs when the points open. It is this change in magnetic field that induces high voltage in the secondary. With the kill switch in the shut position the current just keeps flowing backwards and forwards in the primary windings, and the secondary windings never get any voltage… hence no spark.

Having got your maggie wired in, you may wonder why the ignition cuts out at full noise.
Vertex magnetos can be equipped with an optional speed limiter (part 2040, or GMH part 7406972), fitted under the rotor. The speed limiter automatically interrupts ignition as soon as the engine exceeds a predetermined maximum speed, and switches the ignition on again when the speed has dropped. The speed limiter (as shown in the diagram below) has a spring loaded bow (1), with an adjustable weight (3) above the pivot point (2) of the bow (2).



As the magneto spins faster and faster, the weight begins to move outwards under centrifugal force. This moves the bow upwards until it contacts the electrode in the rotor (4). Once contact is made, the high voltage has two choices: go to the spark plug and jump the plug gap, or take the easy route and flow through the magneto body to earth. The electricity takes the easy route, shorting out the high voltage secondary windings to earth. With no spark the engine speed drops quickly, and the spring tension returns the bow to its normal position. The speed limiter is adjustable, and can be set in the range 1,600 to 4,000rpm (engine rpm, not magneto rpm).

To adjust the speed limiter, the return spring is adjusted. To do this, push the sliding spindle (in direction "a" in the diagram below) with a screwdriver.



This disengages the spindle from a notch, which has twelve index slots. Turning the spindle anticlockwise increases the regulating speed, clockwise reduces it. Each notch is worth approximately 220rpm. The spindle is then pushed back (in direction “b”) with a finger until it re-engages a notch properly. An additional fine adjustment to the speed limit can be made by rotating the centrifugal weight in its eccentric recess. To do this, insert a thin steel wire into one of the holes in the centrifugal weight and turn it, as shown i the diagram below:



The tension of the return spring ends can then be increased or decreased as necessary until the required speed limit is found.

Note that the limiter has a maximum speed of 4,000rpm. This is marginal for a standard grey motor maximum speed (maximum power in a standard grey is at around 4,000rpm), and way too low for a worked hottie. For this reason, it may be necessary to remove the speed limiter in anything other than industrial motor use.

Not a bad idea to check under the cap before bolting up your eBay special.

Cheers,
Harv (deputy apprentice sparkplug tester)

[Harv]

Ladies and gentlemen,

So how do you set the timing with a magneto? Just like a distributor, the motor is turned over until it is firing number 1 cylinder, the magneto dropped in (with the rotor facing #1 plug terminal), and the timing checked.

It is perfectly acceptable for most cars to use a timing light and flash on the timing mark on the flywheel, just like you would on an early Holden with a stock distributor. Non-powered type timing lights are normally fitted in between the spark plug lead end and the spark plug – the high voltage power flowing through the spark plug lead makes the light flash. Some timing lights of this type may not work, as they are made to operate on DC current (the magneto generates AC current). Powered type timing lights operate by having a clamp that fits over the spark plug lead. The clamp senses the current in the spark plug lead, and turns on the timing light (the light itself is separately powered from the car battery). This type of timing light can be interfered with by the large amount of radio interference that a maggie produces. All-up, using a timing lights with a magneto will typically show up one degree late for every 1000rpm of engine speed.

For racing applications, a bit more accuracy is needed. An old backyard method places a bit of cellophane (…like from a cigarette packet) between the points. The engine is then turned over by hand until the cellophane falls out of the points – this is when the points are open, and the engine firing. The position of the flywheel timing mark is then noted.

Another method uses a “buzz box”, a tool about the size of a lunchbox. This method is the most accurate way of setting magneto timing, and is common in the aviation industry. Buzz boxes are available from places like Joe Hunt Magnetos (Joe’s buzz box is shown below).



To use a buzz box, one of the boxes leads is connected to a good earth (say the engine block), and the other lead to the magneto’s kill terminal. When the buzz box is switched on it will buzz, and it’s light will remain off. The engine is turned over by hand until the buzz changes and the light comes on. This is when the points are open, and the engine firing. The position of the flywheel timing mark is then noted.

So how does a buzz box work? The diagram below shows the internals of a buzz box, connected up to a magneto. The buzz box has a small battery, a buzzer, two leads and a small transformer (with primary and secondary windings). The secondary windings of the transformer power a lamp.



We’ll start with the magneto points closed, as per the diagram below.



The current flows from the battery, and through the closed switch. It then has two choices:
a) Flow through the closed points, as per the green arrows above. This is a nice easy path (low resistance), and most of the electricity flows this way.
b) Flow through the transformer primary windings, as per the pink arrows above. This is a tough path (higher resistance), so not much electricity flows this way.
The electricity, having made it’s choice, then flows through the buzzer before returning to the battery. Whenever current flows through the buzzer, it stops and starts (this is how buzzers work). This makes the normal DC current rapidly switch on and off – perfect for making the transformer work (transformers only work with pulsating current… you need the collapsing magnetic field to induce current in the transformer secondary windings, just like a magneto). However, not much electricity is flowing through the primary windings of the transformer. So even though it is pulsating nicely, it does not have enough grunt to make the transformer generate much voltage in the secondary windings, and the lamp stays dark.

We then turn the engine over by hand until the points open, as per the diagram below:



For the purists, I know the magneto rotor is in the wrong position… it should be about 90º clockwise from that show above. Once the points are open, we now give the electricity leaving the battery two different choices:
a) Flow through the magneto coil’s primary windings, as per the pink arrows above. This is a relatively tough path (higher resistance), and little electricity flows this way.
b) Flow through the transformer primary windings, as per the green arrows above. This is an easier path (lower resistance), so most of the electricity flows this way.
We now have a decent flow of pulsating electricity flowing through the transformer primary windings. This generates a decent current in the transfomrer secondary windings (shown by the red arrows), and the lamp lights up. Because the circuit resistance has changed, the tone of the buzzer also changes.

If the light will not go out as the engine is rotated, the points are either staying open or are burnt, thus not making contact. If the light will not come on, there is a short circuit to ground somewhere. This could be caused by a defective wire or a shorted condenser.

Cheers,
Harv (deputy apprentice sparkplug tester)

[Harv]

Ladies and gents,

Following on from the magneto versus dual-point dizzy article above, I will take a bit of a look at dual-point dizzys (I know, I know, they’re not maggies… but they are kinda cool). The pictures below are of my grey motor dual point, a Mallory Model YC:






So why do we want to run a dual-point dizzy on a grey? One reason may be better spark... but first we need to udnerstand dwell. Most of us are familiar with setting the point gap with a feeler gauge (0.028”-0.033” for our grey motor). It’s a little bit rough as you are trying to find the peak of the distributor cam (…and most of us do that by eye). Another method of adjusting point gap is through measuring “dwell”. One revolution of the distributor shaft is 360º. For our six-cylinder grey motor, the distributor shaft cam (the bit that opens the points) has six lobes, spaced 60º apart. Within that 60º of rotation, the points will be closed roughly half of the time and open half of the time. The time they are closed (and hence current flowing to the coil) is referred to as the dwell angle. It takes time to build up the magnetic field in the coil, so dwell time must be long enough to build a decent field. The simple way to think about dwell is that it represents the ignition coil charge time – more dwell = more charge time = better spark. The dwell specification for our standard grey motor dizzy is 35º-41º. Dwell is adjusted by adjusting the point gap – the smaller the point gap, the higher the dwell i.e. setting our grey motor point gap to 0.028” gives more dwell (41º) than if we set it to 0.033” (35º). For those that want to adjust their points more accurately than the feeler gauge, dwell can be measured via an electronic dwell meter (the Stanley Engine Analyser – Digital sold by SuperCheap auto for around $50 for example will measure dwell).

Whilst dwell angle is constant with changes in engine speed, dwell time is not. As engine revs increase, the amount of dwell time decreases. This means that at higher revs, the ignition coil has less time to build a decent magnetic field (or simply put less time to charge). At low revs the coil has enough time to charge, but at higher revs the coil may struggle, leading to weak spark and misfires. Increasing dwell angle (and hence dwell time) can be done by decreasing the point gap, though there is a limit to just how small a gap is workable (too low a gap for example and and wear on the points rubbing block will permanently close the points).

One way to increase dwell time is to use a dual-point (or twin-point) distributor. The two sets of points are wired together, with the second set rotated slightly to make it open and close a little later than the first set. By overlapping the time that both points were shut, the overall dwell angle (and hence dwell time) increases. So the first benefit of our dual-point dizzy is that it lets the coil charge more, particularly at higher revs. A single-point dizzy is shown to the left in the image below, whilst a dual-point is shown to the right:



This is where we need to be a little bit careful, as not all twin-point distributors are the same internally. For my grey motor twin-point distributor, with the points set to the recommended 0.024” the dizzy achieves a dwell of 36º. Remember that the standard grey motor dizzy will give you dwell from 35º to 41º straight from the factory…the upshot here is that using this particular twin-point dizzy gives less coil charge (and hence potentially weaker spark) than the factory dizzy. Truth be known, each of the older type Mallory ZC, ZCM, YC, YCM, YGC and YGCM six-cylinder dual-point distributors gives a maximum dwell of only 38º.
(side note: the Mallory labelling stands for the following:
Z: centrifugal and vacuum advance
Y: centrifugal advance only
C: 24875-B points, 24878 breaker plate
M: distributor set up for the Magspark transformer (coil)
G: Spinner valve on distributor shaft to operate the Holley CentriVac governer)

It is interesting that the current generation of Mallory distributors makes no mention of increased dwell, with Mallory’s website offering “Each Mallory dual point distributors stabilize contact points eliminating point float and bounce to increase coil output.”.

So why else would we run a dual-point dizzy? In addition to running out of coil charge time, another problem found at higher revs in some single-point distributors is point bounce. Point bounce occurs when the two points arms close, then bounce back open. In opening a second time the ignition coil will try to fire the cylinder a second time. In most cases this has no effect, as the coil hasn’t charged much (and in any case the fuel in that cylinder is already burning). Points bounce becomes an issue when the dizzy has turned far enough to send the additional spark to the next cylinder. The next cylinder is still on its way up on the compression stroke, and the early extra spark can lead to serious knocking/pinging. The faster the engine speed, the faster the points are moving, and the more likely they are to bounce. The dual-point dizzy reduces the effects of points bounce as when one set of points is bouncing the other set is still closed, completing the circuit. This means there is less chance of the second spark. So the second benefit of our dual-point dizzy is that it reduces the effect of points bounce, particularly at higher revs.

Another benefit of the dual-point dizzy is associated with pitting. As the points begin to open, there is a tendency for the electricity (the lower voltage stuff in the primary windings, not the high voltage stuff in the sparkplug) to jump the gap. The same arcing can exist as the points are closing and approach each other. This arcing across the points is minimised by the condenser, though still occurs. During the arcing, metal is taken from one of the points contacts and deposited on the other. This pitting leads to irregular points gap, and hence erratic spark. With a dual-point distributor, the first points set to close "makes" the circuit, whilst the last points set to open "breaks" the circuit. Because the make and break functions are done by different contact sets, the two sets of points share the pitting. Additionally, the two sets of points share the current load (most of the time), leading to the contacts running cooler. The combination of less pitting and cooler running means that the points tend to last a lot longer. So the third benefit of our dual-point dizzy is that it reduces the wear on the points, leading to more reliability and less need to change points (albeit there are two to replace).

So all up, for our grey motor a twin point dizzy (or at least the Mallory ones) gives us reduced point bounce and lower points wear, at the sake of increased complexity (there is a reason that twin point dizies are soetimes referred to as "double trouble"). This could well be why the tag on my dizzy reads “Dual Life” rather than “Better Spark”.

Cheers,
Harv (deputy apprentice sparkplug tester)

[Harv]

Ladies and gents,

I noted above that not all dual-point distributors will increase dwell (and hence give better spark) on grey motors. This goes to show how careful you need to be in buying a dual-point dizzy for the grey. My one (a YC476HP) gives only 36º dwell… less than factory, so no additional spark capacity. The one shown below (a YC180M) on the other hand gives 48º per point. Point overlap is typically 9º on the Mallory twin dizzy’s, so the maggie shown may well have 57º dwell – heaps better than the factory grey dizzy at 41º.

It is interesting too that the dizzy below has been overstamped from Z to Y – it must have had the vac advance removed by the factory.







Cheers,
Harv (deputy apprentice sparkplug tester).

[Harv]

Ladies and gents,

One of the big questions is just which ignition upgrade gives the best results. I’m going to assume here that you are looking for an ignition system that at least looks period correct – maggies are OK, twin-point dizzies are OK, Pertronix ignition hidden under a standard dizzy cap is OK, but fandangled electronic boxes are out of scope. Before we look at the comparison, a little note on the Pertronix. Normally I don’t like to work with fancy electronic gizmos, but the Pertronix is getting more and more common, and is cheap… so here goes.

Originally known as Per-Lux, the company was founded as a driving/fog light company in 1962. Per-Lux began making electronic ignition in the early 1970’s (initially for the industrial market), and electronic distributors from the mid 1980’s. In 1990, Per-Lux sold their lighting division, and in 1991 changed names to PerTronix. PertTronix now sells a wide range of ignition components, and provides a points upgrade (as part number 1864A) for the grey motor dizzy. It’s not a perfect bolt-on (there is a little bit of trimming to do to get it to work), but nothing overly onerous – the instruction sheet is here: http://www.pertronix.com/docs/instructi ... /1864A.pdf. The 1864A is a PerTronix Ignitor I module (they do not offer the fancier Ignitor II or Ignitor III for grey motors), often referred to as a “Pertronix” (I will refer to the 1864A kit here as a Pertronix for simplicity). The Pertronix replaces the factory grey motor points and condenser, and fits under the distributor cap (hidden from view). It works by bolting a magnet assembly (magnet ring) to the dizzy shaft. As the magnets rotate, they are sensed by another small box (or sensor) mounted in the dizzy using the Hall Effect. Hall Effect dizzies are nothing new – they were offered by Holden from around 1980 starting with the WB and VC Commodore blue engines, and continued through the VH (blue) and VK (black) Commodores (they were also used on JB and JD Camiras… but best not to mention those). In very simple terms, the Hall Effect unit has a set of magnets spinning on the dizzy rotor, one for each cylinder (kind of like normal dizzy cam lobes). As the rotor spins and a given cylinder’s magnet passes the sensor, the sensor gets excited and switches off current to the coil (kind of like the points opening).

One obvious benefit of the Petronix is that unlike standard grey motor points the Pertronix is mechanically simple, and more resistant to dirt, oil and grease. The system also eliminates points wear and pitting, and does not suffer from points bounce or float. Performance-wise, PerTronix’ big claim to fame is that they deliver twice the voltage to the spark plugs. That’s pretty cool, but how does it do it? The answer lies in how fast the Petronix can switch the current to the coil (the low voltage stuff) off. With a standard set of points, it takes a bit of time to get the points open and stop any arcing. We’re talking milliseconds, not hours here, but remember that the factory grey motor dwell means that the points stay closed (charging the coil) for about 1.6 milliseconds at full noise… there is little time to spare. The amount of voltage that you get out of the coil is proportional to two things:
a) The ratio of wire turns in the primary and secondary windings. Double the ratio and you get double the voltage.
b) The rate of change of the magnetic field. Make the points open twice as fast, and you get double the voltage.
(for those with an engineering bent, the above two things are related to Faradays Law of Inductance). The Petronix uses the second of these two things (the rate of change of the magnetic field in the coil) to it’s advantage. By using electronic bits (instead of mechanical points contacts), the Pertronix can drastically reduce the time to switch off the current to the coil primary windings… in effect, it halves the switching time. This makes the magnetic field in the coil change twice as fast, and hence the Petronix will deliver double the voltage to the spark plug.

Note that this is very different to how the dual-point dizzy works. The dual-point dizzy uses the principle of “give the coil current for more time (more dwell) so that it charges fully”, whilst the Pertronix uses the principle of “turn the current off twice as fast to get more voltage”. PerTronix makes no claim to fame of extending dwell. Measurements made by some enthusiasts on the 1864A installed on a grey motor show the Petronix dwell to be 33.6º (with an air gap of 0.040” – more on the gap below). The Pertronix dwell is lower than the factory grey motor dwell of 35º to 41º. This can mean that at high revs the Petronix may not charge the coil fully (or even as well as a standard set of points), even though the Pertronix will get better voltage due to the faster switching. These two things (less dwell but faster switching) will play off against each other, and are heavily dependant on the coil – a crappy coil that takes a long time to charge may be better off with longer dwell rather than faster switching. This probably explains why PerTronix is somewhat coy about the exact benefits of its product for every user:

“The performance of an Ignitor® is dependent on all of the components in your Ignition system…. Some (customers) report horsepower and/or fuel economy increases beyond their expectations. Others report no real increases, but claim that the fast starts first time, every time, the reliability and the benefits of never having to change points again or perform minor tune-ups is well worth it.”

For those who would like to play with the Pertonix dwell, it is possible to tinker with the air gap between the magnet sleeve and module. The gap is shown by the green circle in the image below (I know, I know… it’s not a grey motor dizzy... it's a Merc).



The reason that changing the gap changes the dwell is because the Pertronix Hall Effect sensor is just a glorified switch. It supplies current to the coil, just waiting for the magnet on the rotor to get close enough.
Once it gets close enough, the sensor turns off the current. In the diagram below, I’ve shown the magnet ring rotating clockwise (by the red arrow), with one of the cylinder’s magnets shown in purple (I’ve only shown one, but there should be six for our grey).



The sensor holds the current on (charging the coil) until the magnet is 5mm away (I’ve exaggerated this distance for simplicity... its really more like 1mm for a real life Petronix). Once it is 5mm away, the sensor turns off the current. If we move the sensor and magnet ring closer (like the image to the right), then the magnet gets to 5mm a lot earlier in it’s rotation. This means the sensor turns the current off earlier, and we get reduced dwell (i.e. reduce the air gap = reduce the dwell, and increase the air gap = increase the dwell).

Be mindful that PerTronix indicates that the air gap is “not adjustable” for the grey motor 1864A kit… there is not adjustment screw, and you would need to modify how the sensor mounts. Some PerTronix users routinely use this trick to get more dwell, and hence a better coil charge (albeit not on the grey motor kit). For example for the 1847A kit commonly fitted to dak-daks, the factory 47º dwell is increased to 54º when a standard Pertronix is fitted with a gap of 0.85mm. Increasing the gap to 2mm gives 58º of dwell for this kit. There is of course a limit to how far you can increase the gap before you either run out of room inside the dizzy, or the sensor can no longer “see” the magnets.

Cheers,
Harv (deputy apprentice sparkplug tester)

[Harv]

Ladies and gents,

As promised, attached below the (grey-motor centric) comparison between original points, dual-points, maggies and those techo electronic Pertonix things .



(... and before anyone asks, coolness is in the eye of the beholder ... or maybe that should be coldness is in the hand of the beerholder ).

Cheers,
Harv (deputy appentice sparkplug tester, trainee beerholder).

[Harv]

Finally, some photos of the elusive Holden industrial engine maggie (thanks Gary):







For those with an interest in the PerTronix info above, I have had a second dizzie measured showing 34º dwell with an air gap of 0.040" (seems to be the standard output), and one other showing 29º (with an air gap yet to be comfirmed).

Cheers,
Harv