Is there an accepted way to add grounding to your distributor? I know it's been mentioned before on our site. Should you just add a grounding strap from the firewall to the bottom side of the distributor with a small sheet metal screw?

 

Not sure what the advantage would be. The hold down clamp should be good enough. There are a bazillion GM cars (and others) running around without it and not having problems.

 

I moved my post and @BillK response so we didn't hijack the other thread. I didn't want to be THAT GUY!

I think the GM HEI modules currently suffer from poor grounding. I know I've changed out more than 1 or 2 HEI modules on the side of the road.

 

Heat transfer paste on the bottom of the module is important. I don't have data to make a comparison to current failure rates; but, HEI module replacement/failure was common enough in the 80's. Some of the current module failure could be related to insufficient voltage to the module from the ignition switch or ground circuits that have developed high resistance over time. I'm not saying there isn't a quality issue with the new modules, rather that there could be other contributing factors to module failure.

 

This site and adding links sucks. Anyway, for HEI, there's a ground strap for the center pin available at most auto parts stores. I'm not sure about points, though. Maybe a ring terminal for one of the screws in the base should work, no?

 

In the early 80s, it wasn't lack of grounding causing a rash of HEI module failures. Although it probably wouldn't hurt it, I've never added grounds to an HEI and never had HEI issues because of it.

The biggest issue was the monster huge spark plug gaps putting undue strain on the modules causing early warranty failures. Circa 1985/86 time frame, GM chose to reduce those gaps to 0.060" from the original 0.080". This dropped the failure rates significantly. This is why you see things like the R46SX OEM spark plug (boxed with 0.080" pregap) replaced with the R46SZ (boxed with 0.060" pregap). Along with ensuring a film of heat sink paste on the base of the module during install, I still bend sparkplugs closer to 0.045-0.050" range without issues.

 

Here's a thread on the HAMB about HEI grounding.

https://www.jalopyjournal.com/forum/...ummies.950499/


I suppose you could run a grounding strap from the top side of the coil with that grounding bar and run it to the engine ground on the firewall.

 

Yes, to both, and that was one of the links.

 

Not that it was mentioned here, but dielectric grease and the thermal paste are not the same!! People all the time use the grease and then wonder why the modules fail.

 

Right you are Matt. The HEI module that just failed on me had been installed with the thermal paste I got from the auto parts store an lage ago (in the ketchup packet) I had a bit more left and installed a spare I had but I think it was bad (the last one that failed that I had held onto).

So, after doing some reading online I found that the thermal paste to use is the same stuff you use on computer chips. I bought some from the International Shopping website. It's got to be better than those ketchup packets.

 

Here's what I use. 3 oz. has lasted me for a LONG time.



GM instructions for module removal/replacement from the 1984 CSM: