Harv's grey motor magneto thread

[Harv]

Paul's grey motor Ronco :

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Cheers,
Harv

[GreyEJ]

That's a nice mag if I do say so myself.

[Dr Terry]

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).

Harv (deputy apprentice sparkplug tester)

I'll begin by congratulating you Harv, on a job well done. I think everyone on this forum admires your dedication & level of research as well as your clear & concise writing style. An absolute asset to the forum.

As many of you would know I've worked in both the electronics & automotive fields for nearly 45 years, 38 of those in my own business. If you include my teen years spent tinkering at home that number exceeds 50 years. With this background I've read your 'enthusiast's guides' with more than passing interest. I've often thought that I should throw in my 2 cents worth, but it hasn't been required up until now.

Don't take this as criticism, just use it to increase our combined wealth of knowledge, but I have a few comments re: the above quote.

You've confused or combined 2 different ignition sensing styles in comparing the Blue 6/V8 distributor to that of the JB & early JD Camira. The distributors fitted to WB/VC/VH (6 & V8), VK (EFI 6 & V8 only) & VL (carby V8 only), all use a reluctor type pick-up for sensing timing position which then drives a separate module to fire the coil. Early Camiras use a Hall Effect system.

The reluctor system uses a 6 pointed rotor which rotates inside a 6 point stator which has windings attached, similar to a magneto set-up (for V8s these two items have 8 points). This creates an analogue 'sawtooth' output to drive the ignition module. Another feature of this system (on Holdens anyway) is that they've used a very high output ignition coil, resulting in a huge spark voltage (typically ~50,000-60,000 volts). They have spark plug gaps of 1.5mm (60 thou) to give maximum fuel burn. They call this system HEI (High Energy Ignition) which was required to reduce emissions as the anti-pollution ADRs came into effect.

Also the later Camiras (unleaded JD & the JE) along with the closely related LD Astra & N13 Pulsar, use a 4-point reluctor system not unlike the WB/VC etc. however they do not use an HEI coil

BTW, DO NOT ATTEMPT to fit a high output or so-called 'sports' coil to any Pertronix module, they will not handle the current & will soon burn out. Having said that, Pertronix themselves market their own 'Flame Thrower' coil which WILL work with their module & produce a good spark, but not to the level of an HEI system.

The method of sensing that the Pertronix system utilises, is not commonly used by the world's car manufacturers. Most OEM systems use either the reluctor system (as described above) or a hall sensor (as in JB/JD Camiras, V8 EFI Commodores & others) or an LED optical pick-up (as seen in VL 6 Commodores & many Japanese cars). The Hall Effect system uses a spinning ferrous drum or disc passing thru the sensor like a chopper wheel. The optical method has a similar very precisely laser cut disc spinning between an LED & a photo-transistor. The reluctor method delivers an analogue signal, while the hall effect & optical systems produce a very precise square wave. Each method has their good points & bad, with none of them proving to be any more reliable or better performing than either of the other 2.

Keep up the good work, Harv.

Dr Terry

[Harv]

Many thanks Dr Terry - appreciated.

Off hand (and purely out of curisosity), which of the V8 Commodores had the Hall Effect sensors?

Regards,
Harv

[Harv]

Ladies and Gents,

The photos below show an item recently put up for sale on eBay. It’s a pretty cool setup, and looks to have been done very professionally. The builder has modified an original GMH Bosch grey motor dizzy to operate with twin points. From the eBay posting, it has been completely disassembled, cleaned and inspected prior to the housing being masked, glass bead blasted and chemically cleaned. The centrifugal advance mechanism was regraphed to provide 22º of advance from 1000rpm, all-in at 3250rpm (standard grey motor is 28-32º of advance from 500rpm, all-in at 3450rpm), with the vacuum advance removed and blanked off. The really cool part is the twin point modification. Holden red motor points (Bosch GB 534) were used, requiring quite some machining. Dwell was increased from the factory 35-41º to some 50º - a great increase to help coil saturation at high rpm. This is neat, especially given that some of the other dual-point coils adapted to the grey give little or no increase in dwell. If anyone is after one of these, try contacting David in Sydney on 0410596365.













Cheers,
Harv

[Dr Terry]

Many thanks Dr Terry - appreciated.

Off hand (and purely out of curisosity), which of the V8 Commodores had the Hall Effect sensors?

Regards,
Harv

The only V8 Commodores to use Hall Effect sensors in their dissies were the EFI versions, from 1988 onwards.

The very first of these was the VL SS Group A (Walkinshaw) which was also the first Holden V8 to use an ECU for engine management. There was no centrifugal or vacuum advance on these dissies, that was all handled by the pre-programmed 'mapping' in the mem-cal section of the ECU. The mechanical part of the dissy was simply a solid shaft, which rotated the Hall Effect drum & the rotor itself.

Without getting to far off the track, the last of the Holden V8s, the VT sequential injection version, had 2 Hall sensors inside the dissy, one for the 8X timing signal & the other to tell the ECU whether it was on the compression stroke or exhaust stroke, effectively acting like a cam position sensor.

Falcon 6-cylinder engines from XF (1984) thru to EL (1998) also used Hall Effect style dissies.

Dr Terry

[Harv]

Ladies and Gents,

For those following the Pertonix information above, I have had a number of dwell results come back.

The dwell on two Pertonix'd grey motors came back at 33.6º@0.040” air gap. A third result came back at 27-28º@0.050". This is interesting, as I would anticipate that increasing the gap would increase the dwell (i.e. a 0.050" gap is bigger than 0.040", so you should get more than 33.6º dwell). i have had one other 27º result from one of the humpy guys, though he hasn't measured the air gap for me yet (pretty pleeeease ).

Cheers,
Harv

[Dr Terry]

Harv.

I don't believe that you can read much into those dwell measurements.

Most electronic systems have 'dwell extension' built in. It may well depend on the actual RPM where these dwell figures were seen.

Dwell extension means, that as the RPM is increased, the dwell is also increased to match, because more dwell is required at higher RPM & load.

Unlike contact points type systems, the dwell is not constant throughout.

Dr Terry

[Harv]

Thanks Dr Terry.

From what I understand though, the Ignitor I modules used in the grey motor upgrades have fixed dwell. PerTronix didn't start introducing dwell extension until the Ignitor II modules. I could be wrong though - I've still got a lot to learn.

Cheers,
Harv

[Harv]

Ladies and gentlemen,

A short post on magneto recharging. I have drawn a lot of the material below from an article written by John Rex for Gas Engine Magazine (November 1986), though note that it is well aligned to information printed by magneto manufacturers including Fairbank Morse and WICO.

The magnets inside a magneto can loose their magnetism, and require “recharging”. The frequency that a magneto needs recharging depends on the permanence of the magnet on the magneto.
It is a furphy that magnetos use up energy to create electricity, and that after repeated use the magnetism will all be used up and must be recharged. The energy to create the spark comes from the mechanical energy required to spin the magneto. The magnet merely acts to convert this mechanical energy to electrical energy. It is also rumored that shock and vibration may demagnetize magnets, however this is rarely seen - magnetos that were dropped hard enough to crack the magnets remain functional, provided the magnets remained intact. A further misnomer is that the Vertex magnets “go off” over time. Early (Pre WWII) magneto magnets were made of quench hardened steel alloyed with chrome, cobalt, or tungsten. This material is not as stable as later materials, and may loose charge over decades (perhaps one third loss). Vertex magnetos however were made of Alnico (aluminum nickel cobalt) and are much more resistant to demagnetization effects and rarely need recharging. As an example, when WICO made the Model X magneto it changed to Alnico magnets, and note in their Service Instructions for Model XH that “the ability of magnet steel to retain its magnetism is known as its coercive property. The magnet steel used in the model XH and XHG rotors has such extremely high coercive value that it is practically impossible for these rotors to lose any appreciable amount of magnetism under any condition. It is therefore, not necessary to recharge model XH and XHG rotors.”

So if the above things do not cause a magneto to lose charge, then what does? Whilst it is very unlikely for a Vertex to lose charge (the Vertex Magnetos Instruction Manual makes no reference to recharging at all, despite having quite detailed overhaul and testing procedures), the following may help:
1. Removing the magnets (and in some cases the armature or rotor) from a magneto (and also installing them) subjects the magnets to demagnetizing forces. Magnetos should be recharged with the magnets installed. It is possible to install a ‘keeper' across the poles, made from soft iron. The keeper 'short circuits' the magnet and prevents charge loss during removal/installation. One difficulty is that a keeper frequently must be a complex shape so the magnets can be removed while the keeper is across them. Note however that the Vertex Magnetos Instruction Manual makes no note of the need for keepers during disassembly.
2. Storing magnetos near each other can cause them to partially demagnetize each other. Store magnetos away from each other by at least 3”. Of course, there are not that many people who own more than one grey motor magneto .
3. Connecting a 12V battery to the magneto kill terminal can demagnetize the magnets (and might burn out the coils).
4. Exposing a magneto to fire or excessive heat will temper the magnet and cause demagnetising. Such magnets may never recover their magnetism even when recharged because the characteristics of the metal have been altered.
5. Recharging magnets by half-arsed methods (inadequate energy to fully recharge them, for example wrapping a few turns of wire around the magnets and 'flashing ' the wire with a 12V battery or arc welder) may demagnetize rather than charge a magneto.

Cheers,
Harv

[GreyEJ]

I know 2 people that have more then 1 magneto. I am not one of them.

[Gary C]

Harv, I actually bought the wico magneto pictured in this thread and once I took delivery found out why it has never been used..

It is wrong rotation for grey motor!

Gary.

[GreyEJ]

Oh man that is disappointing. So toy can't use it? I'd be pretty annoyed. Still looks pretty coil.

[Harv]

G'day Gary,

Damn, that has got to hurt. I hope at least that the seller was honest enough with you to say upfront that they were not sure the WICO would work, or had never been used etc.

I know that you can change the rotation on a Vertex, though have never done it myself. A lot of the old Vertex magazine ads etc indicate it is fairly easy. I wonder if one of the old WICO service companys could do the same for yours? There is a John Deere "tractor mob" called the Gathering of the Green" http://www.gatheringofthegreen.com/ who have had some excellent presentations on early maggie service and restoration by a bloke called John Boyens. You may be able to contact him via the website (I can't find contact details).

Cheers,
Harv

[Harv]

Interesting grey motor electronic ignition set-up for sale on eBay.

http://www.ebay.com.au/itm/Holden-Grey- ... 626wt_1362

It’s an ICE Ignition digital unit, retails around $1,100. It’s built around their 7640MV 7 Amp Street Series Ignition Kit. The distributor is made of 6061aluminium billet, with a hardened and ground 4130 chromoly shaft, high temperature upper roller bearing and oil impregnated sintered iron lower bush. Triggering via Hall Effect. HEI style cap with plug wire retainer and nylon distributor gear. 7 amp Street Series digital ignition control with 16 preloaded, push button selectable ignition curves with dedicated tachometer output. High voltage ICE Pro Series Race Coil and 9mm Pro 100 Series plug wires







http://www.iceignition.com/carburetted- ... t-series_1
http://www.iceignition.com/images/user/ ... 202012.pdf

Dammit... got distracted again . This thread was supposed to be about magnetos.

Cheers,
Harv