Hi guys, I feel like I'm in the wrong forum but I think you C3 people are most likely to know the answer to my question. I have installed a HEI distributor in my 61 and it is not making any spark. The coil, pickup etc tests OK as per GM manual. The manual says that you need a special module tester to check the module. Does anyone know how to test the module at home?

Thanks from across the world and across forums.

http://www.users.bigpond.com/blu61/

 

If you live near a bone yard I would sugest you go and pull an HEI cap module and coil, should not be any more then $20.00 good parts to have. One other thing you could try is make sure you are feeding the HEI with 12V, many of the older GM cars ran a 6V feed to the points distibutor. Other wise the GM HEI is one of the best upgrades you can make on an engine.

 

I have never seen a reliable test for modules, either at home or at a parts store.
I had a car that was having problems with the HEI. It would start and run fine and get me to where I needed to be. Then I would come out and I would have no spark. 20-30 minutes later, it would fire up and run fine. Problem may be there one day, and not come back for several days.
I took the module out a few times and had it tested at 3 different parts stores. All of them said it was o.k. I decided to buy a module (about $20 U.S.) and keep it as a spare.

Sure enough one day the car wouldn't start, I swapped the module and it fired right up. It ran fine ever since.
The only explanation I was ever given is that it might have been failing when warm. But no test would ever show that and ultimately the best test was swapping in a new or known good unit.

Another thing to look at is the pickup coil in the distributor. Those can go bad and give some intermittent problems as well, or just no spark at all.

With HEI's when I have a problem I just start replacing parts, starting with the cheapest ones. When I find out which part was the bad one, I toss the old one in the trash and then keep all the other parts I already swapped out as good parts for when I have problems later on. See if you can borrow a known working module to find out if your's is the problem. There are really only 3-4 parts so process of elimination should not be too hard.

 

Thanks for the help guys. Problems are: I live in rural Australia, the nearest boneyard that would have a chevy HEI laying around would probably be in Sydney - 2000km away from me. The nearest place I can buy new parts is 1200 km away. The distrubutor is a rebuilt unit that I bought from a speed shop about 2 yrs ago and has been sitting around waiting for me to finally need it. Most of the parts in it are new - cap, coil, rotor, module, but not the pickup coil. The pickup coil tests OK with the ohmmeter. I have done away with the ballast reistor and am feeding it a full 12 volts. There is just no spark at all happening so I guessed it must be a faulty module. I guess it could be a problem with the pickup coil.

We Aussies are dedicated to our vettes!

At this stage I need to phone the shop I bought it from and see what they have to say about it.




[Modified by blu61, 1:43 PM 5/6/2003]

 

blu61,
I don't know how deep you want to test the HEI module, but I would do this at home to test the pickup coil and module for functionality, without fancy equipment:

Supply power and ground to the dist (Red and black wire). Connect the DC Volt meter (set to max at 20V) + to the brown wire and - to ground on the Dist body.

When you slowly spin the dist shaft (Clockwise), you should see the voltage fluctuates between 0-12V. If you see a constant 12V, the HEI mod or the coil is open; 0V would be a short.

Testing the coil with an Ohm meter staticly is fine, but if the wire broke internally and vibration applied, you will see the intermittent problem.

Don't foget, heat is another factor to these electronic component problems.

Let me know if you need more help!

 

Thanks for the help everyone.

Turns out it was a faulty module. I replaced it and suddenly there was spark!. The pick-up coil looked old & ratty so I replaced it while I had the distributor on the bench. New engine fired first time after re-installing the distributor. It was quite loud with open headers!

 

OK, the way to test any HEI is really simple, of course it's helpful if it's in the failure mode when the tests are ran. ....otherwise all bets are off.....

first off, see a full 12 volts on the thick red wire, engine still, but key ON....
then on the 'tach' wire see the same 12 volts, if NOT....the coil is bad, no question about it.....IF you do have 12 volts on the tach wire, and the thing is still dead, NO SPARK, you either have a bad module OR you have a defective most likely OPEN sending unit coil....they DO fail with heat and open up, hense no trigger for the module to fire on.....

if the spark coil opens up, and they can be intermittant too....the wire if fairly thick so it's not just a bad construction in the windings that heats/cools and opens the wire up.....it's the crimp connections on the two terminals, red/wh/yel depending....they crimp the connectors right through the formvar magnet wire insulation,....a VERY BAD PRACTICE....can cause all sorts of open coil symptoms....I have caught one of these pants down proven, soldered the connections on that coil and never had another problem...
symptom....no 12 volts on the TACH lead....

obvioulsly an HEI needs a good solid HARD 12 volts, not that series wire resistor found on most points ignitions in GM....

GENE

 

blu61
I will be going to the local bone yard, If I see a gm module I will pull the sucker, should not cost anymore then $5.00 or $0.0 I will mail the item to you, you pay cost plus shipping. Drop me line if you are interested.

 

Thanks for the offers and the help, but I have it working now after replacing the module. I also replaced the pick-up coil while I was there because it looked quite ratty.