86 Cutlass loosing spark after about 1 minute

[Audio96]

A while back I had an issue with my Cutlass. Decided to let the car run, since it hadn't run in about 3 months. Was running in the garage and the car stopped running after about 20 minutes.
The temp was pretty high since it was in the garage, but no hose blew. No leaks .
Afterwards the car wouldn't start. Someone on the forum told be to check for a spark by pulling the 1st spark plug and checking to see if i was getting a spark. Nothing.
Per the recommendation, I installed a new coil and I got the car to run for about a minute (THANK GOD I DIDN'T BLOW UP THE ENGINE) ... then it just stopped again. Won't start. Just cranks.
Not sure what it might be. I just bought a new distributor cap and rotor and will see if that will help.

Questions:
1) Is it easy to burn out a HEI coil? I found a video that shows how to check the coil with an Ohm meter and it appears to be "OK".
2) I have a feeling there may be an issue with the grounding strap from the distributor. Maybe?
3) Is there anything else I should be checking?

 

[69hurstolds]

We'll assume it's a 307 since you didn't mention it. But I don't know. Just assuming.

The coil should have a red/white wire setup on it. NO YELLOW wire. Polarity would be different otherwise. GM p/n 1876209, 1985474, or 12498336, or aftermarket equivalent. Again, assuming 307.

My money is on the 7 pin ignition module under the distributor rotor has conked out. Various GM p/ns, like 1987744 and 1978617, and others. But also you can get Standard LX315. Make sure you use the heat sink paste packet that comes with the module. Not just any silicone grease. Needs to be HEAT SINK.

Someone else mentioned the Holley 7 pin modules for GM HEI being good. Never tried them personally.

Of course, all this changes if it's not a 307.

 

[SoFloG]

Most likely the module.

 

[Audio96]

We'll assume it's a 307 since you didn't mention it. But I don't know. Just assuming.

The coil should have a red/white wire setup on it. NO YELLOW wire. Polarity would be different otherwise. GM p/n 1876209, 1985474, or 12498336, or aftermarket equivalent. Again, assuming 307.

My money is on the 7 pin ignition module under the distributor rotor has conked out. Various GM p/ns, like 1987744 and 1978617, and others. But also you can get Standard LX315. Make sure you use the heat sink paste packet that comes with the module. Not just any silicone grease. Needs to be HEAT SINK.

Someone else mentioned the Holley 7 pin modules for GM HEI being good. Never tried them personally.

Of course, all this changes if it's not a 307.

Thanks for the info. I figured it might be the control module. I just ordered a replacement today, Yes ... I have the stock 307. You mentioned the HEI wires. "NO YELLOW wire". Here is a photo of the coil I have been using in my car for years without issues. It has a yellow wire. I ran the Ohms test and it appears to be OK. I'm guessing the control module might be the thing that is causing the issues. It has "GM" stamped on it and may be the original one - 37 years old. I'll install the new control module and let you know how it goes.

 

[69hurstolds]

The magnetic polarity is reversed on the GM red/yellow and red/white wire coils. This can cause harder starting and low rpm misfires. Probably not noticeable but put the right coil in and I'll bet you can notice. The CSMs even mention about matching components between the pickup coil and the main coil, but unfortunately, they don't go into detail as to why.

Some people will say it doesn't matter. Those are the uniformed. But if they make different pickup coils to match with different coils, what makes these "wizards" of coils believable? They're not. GM didn't do crap for no reason.

I'll say it again. RED/WHITE on your Cutlass 307 HEI Coils. Whoever sold you a yellow/red wire deal is not well-versed in GM HEI. That's all I can say.

 

[Audio96]

Wow. Thanks for the detailed info.

And the verdict
Got the new ignition control module, distributor cap/rotor, and new HEI (red/white wires) installs. Started right up and really runs smooth now. Those miss-fires I was hearing seems to be gone.
I've always noticed that the car sometimes misfired here and there when idling and couldn't never figure out why. Nothing major but noticeable to me.
THANKS SO MUCH FOR YOUR HELP ON THIS. This really made my day .... also I'm in the process of getting the Cutlass prepped for painting (oh ... that's my wife's 1980 vette)

Side question: Is it a 307 or 305? VIN: Y
When I look for parts and such I sometime see 305 or 307 listed. What's the difference? I have a 1986 Cutlass Supreme VIN: Y. It's not a hurst/422. Has a 3 speed trans. Nothing special .. but i love her anyway.
Looking for a definitive answer. People always ask me if it's a 305.

 

[PVDave]

When I look for parts and such I sometime see 305 or 307 listed. What's the difference?

While Chevy built a 307 back in the early seventies, in the G-bodies the engines are completely different. They have no interchangeable parts (outside of carburation and ignition).

Easiest way to identify them is to check the oil fill- The Olds has a fill tube in front of the intake, the Chevy fills through the valve covers.