Running issues, now dead

[Breakzero]

See this is the dizzy. Its doing my head in now, I just want to fix the car

 

[jonbills]

I think you have there the 4 pin GM HEI conversion, popular in the US. You'll find lots of threads on it on classiczcars.com.
The module receives a square wave signal from the sensor in the distributor. When the signal is high, the module grounds the coil primary -ve, charging the coil and when it goes low it disconnects the coil primary -ve, inducing the secondary to discharge (spark). So: with an analogue multimeter you should be able see the sensor signal flipping between 0v and (12v or 5v?). And you should be able to see the coil -ve flipping between connected to battery -ve and disconnected.
If the sensor signal isn't happening, the problem is in the distributor. If the coil signal isn't happening, the problem is the GM HEI module. If both are working, the problem is the coil or leads or the distributor cap or rotor.
I reckon. Maybe.

 

[Breakzero]

I think you have there the 4 pin GM HEI conversion, popular in the US. You'll find lots of threads on it on classiczcars.com.
The module receives a square wave signal from the sensor in the distributor. When the signal is high, the module grounds the coil primary -ve, charging the coil and when it goes low it disconnects the coil primary -ve, inducing the secondary to discharge (spark). So: with an analogue multimeter you should be able see the sensor signal flipping between 0v and (12v or 5v?). And you should be able to see the coil -ve flipping between connected to battery -ve and disconnected.
If the sensor signal isn't happening, the problem is in the distributor. If the coil signal isn't happening, the problem is the GM HEI module. If both are working, the problem is the coil or leads or the distributor cap or rotor.
I reckon. Maybe.

Thanks Jon. Excellent analysis!
So in layman's terms, I need to test various points from the module and coil etc to see where the voltage signal doesn't flick between 0v and 5v and or 12v.
Then I should be able to work out which component has failed.
Sorry what point do you refer to as "sensor" what sensor?

 

[Breakzero]

Thanks Jon. Excellent analysis!
So in layman's terms, I need to test various points from the module and coil etc to see where the voltage signal doesn't flick between 0v and 5v and or 12v.
Then I should be able to work out which component has failed.
Sorry what point do you refer to as "sensor" what sensor?

Got you now! Had to go back to the beginning. Sensor in dizzy. Thanks very much Jon all seems logical now.

 

[Breakzero]

Hello Jon and gurus.

So I have just tested again, but this time basic voltages across the module. Here is the results. Voltage going in on coil side is 12.4v, voltage coming out on dizzy side is zero volts. This is also during turning over the engine.

Surely this means the module is dead?
Or do I need to further test at the dizzy sensor?

 

[jonbills]

I think you need to further test the sensor. It will be zero when the distributor is not turning. It will switch between (12 or 5v) when cranking, as each of the 6 teeth pass the sensor. The module uses this signal to charge and trigger the coil.
if you use a digital multimeter, it'll probably be too slow to see the switching, and might just read an average (2v? 9v?). Hence you need an analogue one, something like this: https://www.ebay.co.uk/itm/255647037649

 

[Breakzero]

I think you need to further test the sensor. It will be zero when the distributor is not turning. It will switch between (12 or 5v) when cranking, as each of the 6 teeth pass the sensor. The module uses this signal to charge and trigger the coil.
if you use a digital multimeter, it'll probably be too slow to see the switching, and might just read an average (2v? 9v?). Hence you need an analogue one, something like this: https://www.ebay.co.uk/itm/255647037649

Roger that. I have an analogue meter. Ordered amazon last night come this morning!

At which point should I put the probe on the dizzy?

 

[jonbills]

Put the probes on the distributor side of the igniter.

 

[Breakzero]

Hello again.
So I have replaced the ignition control module now I have spark again. But the car still fails to run and just back fires out the carbs very badly, not even popping like combustion in the carb.

I have checked the firing order and when correct the car will not start at all just turns over and backfires. However when 3 and 4 are swapped on the engine block it tries to start. However still back fires out the carbs.

I did have the distributor off to clean and inspect. I'm guessing the issue is now distributor related as it seems the firing order is out or something strange...

Where do I go from here?

 

[johnymd]

The firing order will be the same for all L-series engines so connect the plug leads to the distributor in the correct order. You may find that the distributor at some time in the past is a tooth or 2 out so you need to identify which plug lead on the cap to start your firing order from. I have had a car fire but not run because the leads were rotated 1 position. Identify where the rotor arm is pointing when number one piston is at TDC then you know which point on the cap is plug 1. This is only if the plug leads have been off since the car was running fine.

 

[Breakzero]

Thanks johnymd and Jonbills. Finally cracked it!
So after sorting the spark issue, went back to basics like you suggested. TDC the engine, checked the dizzy and it was 180 degrees out! So it appears I was chased my tail half the time by setting the spark sequence to the book. As whoever build the engine had the dizzy 180 deg out.
So I must have made it hard for myself at one point when I took all the plug leads off to check timing was right when the ignitor broke. Not knowing the ignition sequence was wrong but right all along!
Runs sweet now just like I remember a straight six runs!
Kudos guys.

 

[Robotsan]

I thought it was impossible for the dizzy to be 180 out, due to the spline on the oil pump that it fits onto only allowing it to go one way?

 

[johnymd]

It’s caught me out in the past so I always check where the rotor arm is pointing at no1 tdc compression.

Glad your now enjoying the zed again.

 

[toopy]

I thought it was impossible for the dizzy to be 180 out, due to the spline on the oil pump that it fits onto only allowing it to go one way?

I'm not 100% sure, but i think the oil pump drive itself can be installed 180 degree out, hence the issue.

 

[johnymd]

The oil pump drive can go in any position. Ideally insert it as in the manual but it can go in any position and you he car will run fine as long as you move the plug wires around to suit. The only issue you may have is the leads could be the wrong lengths.

 

[Breakzero]

Yes correct guys, dizzy can't go on wrong due to offset semi moon shaped location rod thingy.
The previous owner must have installed oil pump drive 180 out. But I never knew until I come to diagnose and fix this non start issue.

Great support on here thanks very much. Went for a spin last night runs fairly well, more to do but progress is progress.