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
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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.
