fbekholden.com

I’m looking to get hold of both a grey motor and red motor cam. I’m after ones that are old, manky and fit for the scrap bin. The bit that I am interested in is the distributor drive gear, and the 4-6” of cam on one side of the gear. Happy to pay postage, but hoping to get a junk cam for free.

For the curious, I will take the drive gear, and machine down the 4-6” of cam to make a shank that that will fit into a drill chuck. I will fit the shank into a right-angle driver, and put the driver onto my drill press. This will give me a drive gear running horizontally. I’ll jig up a grey (or red) motor dizzy so that I end up with my drill press running the dizzy in the normal vertical position.

Now here’s where the fun starts .
I’m going to do some testing on early Holden ignition systems, and compare them against each other under load. So far the lists of testes are:
a) standard Holden grey motor Kettering ignition system (either Bosch or Lucas) – distributor and coil. Mechanical advance only.
b) standard Holden grey motor Kettering ignition system with coil replaced by a Bosch GT40 coil.
c) Scintilla Vertex NV6 magneto with fixed advance.
d) Scintilla Vertex NV6 magneto with mechanical advance.
e) Red motor Scorcher ignition – standard Holden coil.
f) Petronix Ignitor I (model 1864A) electronic ignition system – standard Holden coil.
g) Petronix Ignitor I (model 1864A) electronic ignition system with Petronix Flamethrower 40,000V coil (3Ω, 12V part number 5903: 40501 for chrome or 5905: 40511 for black).
h) Mallory Double-Life model YC476HP dual point distributor – standard Holden coil.

By changing the drill-press belt configuration between tests, the drill press allows for the following speeds (remember that dizzy speed is half crankshaft speed):
Distributor Crankshaft
160 320
195 390
290 580
310 620
420 840
470 940
490 980
610 1220
680 1360
740 1480
765 1530
1490 2980
1550 3100
2350 4700
2410 4820
3645 7290

12V power supply is taken from a standard car battery. The secondary ignition system is connected to six spark plugs mounted in a metal rack, earthed back to the battery. Spark plug gap is going to need to be a bit bigger than standard – I’ll use the values in the Vertex overhaul manual. Distributor speed is monitored by a hand-held digital tachometer. Coil temperature is monitored via a hand-held infrared thermometer.

Now for the cool bit. I managed to lay my hands on an oscilloscope (with many thanks to the gentleman who sorted it out). The kids think I’m setting up a secret lab. This will measure some 0-600V and 4-10A on the primary side. I’m looking for peak voltage as a reflection of primary circuit capacity (higher voltage = more ability to provide higher voltage in secondary circuit). Also looking for evidence of lower primary voltage at higher distributor speeds (insufficient coil charge time). Tests to be conducted over a period of time until coil temperature stabilises, and both initial and final test values compared to evidence the effect of heat soak and increased primary winding resistance.

I need to do some more homework, but with some jiggery pokery I should also be able to measure the secondary side (60kV and 10-100mA). I really want to measure the secondary current too. Looking for peak voltage as an indicator of the ability of the secondary circuit to ionise “difficult” air/fuel mixtures. Looking to measure spark duration as opinions vary as to whether a long or short spark is better. Looking to calculate ignition energy (volts x amps x time) as a measure of the overall energy put into the air/fuel mix.
This is no rush project, and I still have a lot of electronics learning to do… should be fun though.

Cheers,
Dr FrankenHarv.

Ive got a black 6 cam here that's yours if you want it mate.

and if a black 6 cam is no good i have a red 6 cam that i can bring down the next time i come which should be mid week

Dr FrankenHarv,

Does this project need to be run past the Holden ethics committee or the Telecommunications Authority to receive approval before you proceed?

Best of luck with it and look forward to your findings.

Regards
Stephen

In the Shed wrote:Does this project need to be run past the Holden ethics committee or the Telecommunications Authority to receive approval before you proceed?

Sshhh... they'll hear you. That's why it's a Secret Lab. I even have the tinfoil helmet just in case one of those Telstra vans is trying to read my mind (not that there is much of my mind to read... more like a kids picture book with a few pages missing and crayon scribbles on the rest).

Craig, Mick,

Many thanks - appreciated. Are red and black dizzies interchangeable (ie the cam gear identical)? I'll grab the red cam please as I have at least three red dizzies to test (standard, a Scorcher and a maggie).

Cheers,
Dr FrankenHarv (master of the Scintilla Shuffle).

Yes, black and red dizzy gears are the same.

Cool - looks like the black cam is the one to use then. It'll save Mick dragging the red one all the way down here.

I've got to line up an expedition out to Dave's next week to take a look at the wagon (probably Wednesday). I'll give you a shout once the timing firms up (may have to make a front-veranda pickup on the run).

Cheers, and thanks again,
Harv

i've got the red one in the car and have to go to smithfield while down there so could probably drop it off if you want

Easy as Harv.
However it works out is good.

Thanks Mick - sounds like the red one and a drop-off en-route to Smithfield is the go (wish I could make up my mind ).

Thanks gents,
Harv

All sorted.

Some interesting results.

Mick dropped off a red motor cam this week (many thanks - appreciated). Out of curiosity, I measured up the red motor distributor drive gear, and compared it to the grey motor cam one (I used the cam that is destined to go into my Norman-blown meth monster project). The gear is near identical on both cams - 1.74" diameter, 13 teeth and 60 degree helix angle. The only difference is that the red motor gear is wider - 0.615" compared to the grey at 0.515".

Looks like I will be able to use the red motor cam for both red and grey motor dizzy testing.

Now all I need is someone with a lathe who can cut the cam down so that it becomes just a gear and spindle.

Cheers,
Harv

Hey harv did you find any one to do that machining for u? Which side of the cam gear do u want the spigot ?

G'day Browny,

No, still need someone to do the machining for me.

What I need to end up with is the gear with nothing hanging out one side (kinda like how the timing gear looks on the end of the cam), and about 4" or so of spindle hanging out the other end of the gear. The spindle diameter needs to be small enough to fit in my drill chuck (gotta measure that). The rest of the cam then becomes scrap.

Cheers,
Harv

No worries just let me no what diameter to suit ur drill chuck will prob be around 10-13 mm and I will spin it up for u. Have a cam here ready to.go

Awesome - very much appreciated.

The shank that needs to hang out the end of the dizzy drive gear can be 10mm diameter please (my right-angle driver is smaller than the drill press).

No rush at all - I'm back on the road for work again shortly (gotta lotta oscilloscope reading to do).

Cheers, and thanks,
Harv