ffvetteman

My dads car is a 77 Vette with a zz4 crate motor. It was a full RTR motor that came with everything. The first coil went out so I had a spare one to put in. Put that in and it ran fine for about a year. Started it one night to move it over and it ran fine. The next day went to start it and it won't fire, no spark. Look like another bad coil. I've got one more spare to put it but was there anything I should be looking for causing coils to go bad?

Could it be a heat issue and should I look at getting a different coil lika Accel? Checked the wiring and all looks good. 12 volts at distributor. Gonna try the spare coil tomorrow but just wanted to get other opinions as to what the problem could be. I did also put in a dist module just to be sure. Still no spark.

69427

Got any info on the coils and modules to see if there's a compatibility issue? What brand is the distributor (and coil and module if different)?

Marlin

There are 2 differant HEI coils, they both look the same and fit as well. What color are the wires on the coil leads?

ffvetteman

Sorry I didn't clarify further. The distributor came with the motor so it's a stock (I'm assuming) GM coil. The second one I put in there was in fact a used one out a motor in a car I'm restoring. That motor I pulled the second coil from was out of a 77 Chevy pick up truck. It was running when I pulled it and after i put in that car but has not run in many years. And it looks like that coil and distributor was original to that truck. Same style coil with the ground that goes from the pin to the bottom of the coil and is held in place by the bolt that holds the coil in the cap.

I hope that makes sense.

ffvetteman

Now I pulled the coil from the original 77 Vette motor to try in the new motor but was thinking about buying an Accel coil to use

ffvetteman

And the coil leads were all the same color. Red for power, yellow for tach and black for ground. The modules should all be original GM.

The coil that just went out was in the car for about a year and worked fine that whole time.

TWINRAY

I used 2 Accel coils in the past in 2 different vehicles - a '75 Blazer that I sold (actually gave away) and the wife's '79 Camaro (still have it ). Both worked well.

7T1vette

You may also have a problem with the distributor cap. There are 'molded-in' strip conductors to electrically connect things. Sometimes the thin plastic that separates those strips breaks down and can cause an electrical short or gap-jumping of the signal. This could be the primary cause for your coil failures.

Look carefully at the cap. If you are not sure, replace it.

Kacyc3

for a little more than the accel coil you are thinking about you can get a much better MSD and I would recommend them over accel.

ffvetteman

Thanks for the replys, but I have an update. I put in the other coil and it fired right up. So just for fun I took the coil out and put in the coil that would not start the car and it started. So it's not the coil after all

Now I'm confused. While it would not start, I had 12v at the coil from the car. I switched modules from another dist and it still would not start. Today I go out there and it starts with the same parts in it that were in it when it would not start.

The only other thing I can think of is could I have had a bad ground on the spark plug when testing for spark and the problem was the engine was flooded? (poss from my dad touching the gas when he tried to start it, since he is not sure if he did or not). Or is there a problem with that other part in the dist.

Unfortunatily I will not be able to tell until this happens again.

I did check the cap and all wiring in the dist carefully and did not see any ware or anything out of the ordinary.

7T1vette

Given the 'symptoms' that you have described, I would pitch the distributor cap and buy a good quality (not from 'the Zone') cap.

wcsinx

I find that 9 times out of 10 when that happens with electricals, it's because you had a poor connection somewhere. And removing and reinstalling resolved it at least temporarily. Clean everything, spray down with electrical cleaner, make sure all the female wire clips are still tight.

And FWIW a poor connection to the coil could very well shorten its life.

ffvetteman

The cap is the one that came with the crate motor, and believe me I do not use cheap parts on anything ever. Only buy quality name brand parts even though I pay more.

I thought of the electrical and agree, but in this case everything is new with the motor, dist and everything. The only exception is the red power wire to the dist which I cleaned. So at this point I'm not sure what the problem is. I did check all the wiring/connections in the dist and all looked good and clean.

I know about old wiring, I have had my fair share of issues with my 84 Vette with 182k miles!!

Again thanks for the replys and if anyone else comes up with an idea please let me know even if it is obvious, sometimes we miss the obvious!!!

tyancey00

I had a "red box" on my motor and every so often it would burn a coil. I took off the box and it has not done it again. I think the box may have just been bad. it took 3 years to figure this out....