I hope someone can give me some direction on a problem I have been having. I rebuilt the engine in my 1981 Corvette with new heads, cam, intake, exhaust, Edelbrock carb, and MSD Streetfire distributor. I have disconnected the CCC harness and nothing is connected to the distributor because it is a basic HEI with only tach and battery connections. I can get it to run and drive but after maybe 20 miles of driving it starts to misfire and sometimes backfire through the carb. I am able to limp home and put it in the garage. The next time I try to start it, nothing happens. If I replace the ICM it will start right up. But every couple times I replace the ICM, the coil goes bad as well.

Some folks have suggested that I rewire everything based on a 1980 or older Corvette to eliminate any chance that the CCC is changing the voltage through the coil and ICM and frying them. I thought that once the harness was disconnected from the original distributor that the computer was completely disconnected and not affecting it, but I just pulled the computer out so there is no chance that it is affecting anything. I have multiple engine grounds as well.

Before I spend another $100 on a coil and ICM, is there anything else that I should double, triple, quadruple check? This started as a Covid-project when I bought it in August 2020, and would like to drive it to Corvettes at Carlisle this August.

Thank you for any help!

 

I didn't see carb change?

 

Have you checked the alternator output voltage?
Have you checked the voltage at the BAT terminal on the distributor?

 

Changed the carb to Edelbrock 1913 800cfm with electric choke. That is what Edelbrock recommended for the EDL-2098 top end kit I installed.

 

Voltage at the BAT terminal is 12V with the key on.

I have not checked at the alternator. Where should I check that?

 

Yes, voltage check, I know of no way ccc can do what you say.

 

I'll check the alternator and see what that is putting out. I guess I have to get it running and update you. Its the original alternator so maybe it decided to crap out after 40+ years

 

Check it with engine running. The output terminal of the alternator.

 

Thanks! I will check that out in the next couple days. Hopefully that is it and can just swap it out without any more electrical guessing games.

 

raise rpm

 

Correct. The CCC only effects three things, carb mixture, timing advance and torque converter lockup. By replacing the distributor and carb the OP has essentially neutralized the CCC. Whatever is causing the problem, it isn’t the CCC.

 

You need a solid 12v source to begin with so check yours....it should be 12ga back to the fuse box keyed on......
In this case...if the 12v is ok....then throw the distributor in the trash and start over.......this is your control for this experiment Lol......
I recommend the MSD HEI (expensive but best there is), the Davis DUI, or the GM Performance crate HEI.....stay away from the China units for $100 that look pretty.

Jebby

 

As others have stated, there is nothing in the CCC that can cause this issue on your 81. Just a thought here but how many wires do you have plug into the distributor? You should have the main 12 volt power wire, the tach wire and a ground wire. You should also have a ground strap /metal strap running from the HEI coil in the cap over to where the wires plug into the cap. It is the one that kind of hides behind the power wire and tach wire where they attach to the cap/distributor.

 

This is a good point.......make sure that guy is in there....if not, you can have all kinds of issues.

Jebby

 

I didnt think the CCC could have done anything since it was completely disconnected, but a Corvette "specialist" suggested that was the problem. Its gone now, so I dont have to worry about it.

I have an MSD 8362 Streetfire distributor, and replaced the coil and module a couple times when they would burn out. I'm guessing it is junk and I'll look into getting a new one.

I have 12V to the BAT wire at the distributor when the key is on, but cant test it when cranking as my arms aren't long enough to reach.

 

The distributor has two wires connected, the 12V and the tach wire. It does have the ground strap from the coil that then has a prong where the wires from the module connect. I assume that ground strap from the coil is then grounded through that wire to the module, which is then grounded through the distributor housing. Is there any other ground wire on the distributor?

I feel like just getting a new distributor and alternator to start from scratch.

 

You have to test it with the engine Running

 

Buy some leads with alligator clips at the end. Then you can sit in the car, crank, listen to tunes, whatever, and see the voltage displayed on the multimeter on the air cleaner lid or laying on the windshield.

 

Make sure you have heat sink compound (not dielectric grease!) underneath the ICM, or you will continue to fry them.

Also the IGN terminal on the fuse panel (if your year still has it?) is a good place to supply 12v for the distributor. It’s 12v key on and cranking. Use a good size wire though, like 12 gauge.

 

Streetfire ignition replacement should be the starting point , I'm with Jebby on that China stuff is garbage