Problem with 383 distributor, (earthing issue?)

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ozmoparjoe

ozmoparjoe

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Hi everyone, got a real strange one this time. I have a newly rebuilt 383 on a test run stand and it has a Proform distributor with the GM style HEI conversion. So the other day we went to start it to break in the cam etc and no spark. Checked everything over and over and found that it has no spark while cranking over, but if I take the distributor out and spin it by hand it sparks!
Also gave me a shock holding it.
Anyone had this problem before?
I also tried the old (Petronix converted) distributor, with ballast, and same thing.
Battery is new also with 1000 CCA.
Any advice appreciated thanks.

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Nope but interested in the findings! Almost sounds like a bad ground path?
 
What are you using for a switch on the test rig? You may not be getting 12v to the ignition when cranking
 
Next thing I'd do is measure the 12V to the ignition...........between the ignition power and the engine block WHEN CRANKING and see what you have. If it's below 10.5v I'd say you have discovered the problem area
 
67Dart273 said:
Next thing I'd do is measure the 12V to the ignition...........between the ignition power and the engine block WHEN CRANKING and see what you have. If it's below 10.5v I'd say you have discovered the problem area
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Yeah I need to buy a multimeter and check it!
 
That looks like a Bosch module, not GM. The pick up wires that would normally be connected to the GM module need to be reversed, ie, the wire that goes to the small terminal on a GM module needs to go to the large terminal, which from memory is the outside terminal on the Bosch.
Having the p/up wires reversed will still generate a spark, but at the wrong time.
 
Bewy said:
That looks like a Bosch module, not GM. The pick up wires that would normally be connected to the GM module need to be reversed, ie, the wire that goes to the small terminal on a GM module needs to go to the large terminal, which from memory is the outside terminal on the Bosch.
Having the p/up wires reversed will still generate a spark, but at the wrong time.
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yes, you're right it is a Bosch, my mistake, i have reversed the wires but did not make a difference unfortunately
 
This may have been mentioned before - you CANNOT troubleshoot electrical issues properly without a voltmeter/multimeter. It's a basic tool, like a set of wrenches.
 
Demonic said:
This may have been mentioned before - you CANNOT troubleshoot electrical issues properly without a voltmeter/multimeter. It's a basic tool, like a set of wrenches.
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you sound like me. WHAT YOU NEED to troubleshoot these old girls electrically

1...A multimeter. Try to get something better than Horrible Freight. For around 5-80 bucks you can get some decent quality, still China built. For the same price if you are careful you can get a "previously owned" Fluke 70 series. I HAVE 5 OF THEM although I use them for more than automotive

2....A 12V test lamp. I prefer a "real" light bulb type but the LED ones can be useful.

3...Although VERY useful is an old stop/ tail lamp socket and an 1157 or 1034 bulb. You can wire this many ways for different purposes

4....At least 2 and better 4 alligator clip wire leads. You can buy these various places, ebay, or you can buy alligator clips and make your own. Also very useful sometimes is a rag-tag clip lead long enough to reach from the battery to any other point on the car, IE from front to back

I am big on voltage readings AND NOT continuity or "ohm" (resistance) checks. This is because in cases of losing power, often switches or connectors "can check OK" under the low power of an ohmeter, but stop functioning under heavier functional load.
 
Hey guys just thought I'd share that after all the time spent chasing this problem it is fixed, I adjusted the gap on the relictor to .008, and cleaned the paint off the distributor clamp and now seems to be working as it should.
Thanks for all the advice.
 
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