Hei

I had been having trouble getting my 71 V6 with a three year old Napa HEI to start all winter. Sometimes it would, sometimes it wouldn't. Final nothing would get it to catch. I took a plug out, stuck the wire on it, gounded it and check for spark. Nothing. Check the "bat" wire voltage when cranking, 9.5 volts. I had an old HEI so I swapped out the electric spark control module. It started right up! If you buy a rebuild Napa HEI distibutor you'd better carry a spare control module.

 

That's not unique to Napa distributors. That's standard for any GM HEI. Always carry an extra module. Always put silicone dielectric grease between the module and distributor body to help dissipate head as well.

 

Thanks for the reply. I won't want to cast dispersions on Napa. When I removed the defective module the grease was white. I assume that it was still silicone.

 

The white stuff most likely was dielectric grease. It usually comes out of the tube clear but turns white over time. Not sure if it's from heat, moisture, or what.

 

I read something recently that said the heat sink grease for the HEI module is not the same as dielectric grease. I think it was the Rich Motts article. Anyway, it's just one of those things I wonder about sometimes. . . .

 

sorry to hear about the module failing. ive only heard about one other failing and that was a ford unit, the truck was only 8 or 9 months old at the time. i have a chevy with a hei and put well over 200,000 miles on it with out any problems. also have one in my 350 sbc in my jeep and havent had any problems. the old saying is that points will never let you down but sometimes they can be a pain. more than likely a rare instance for it to fail.

 

i love my hei..woot!
i put the excell super coil on it @like 55kv or something. it didnt have issues firing anywhere. i had it sent to an old skewl mechanic to redo the springs and weights and he removed the vacuum advance an set it to mechanical only, starting at 8 deg btdc. max advance was like 32 deg with super unleaded it just ran awesome...and then it died..
lol
coming back together soon though.
try the excell coils and spiral core wires. they are a lil pricy, but man...

 

When we did the Rubicon run a few years back there was a guy in a Bronco that did not carry a spare module. He spent 2 or 3 extra days on the trail, was running out of food and water. I always carry a spare now.

 

Yeah, I see it as no different than carrying an extra condenser or points if running old school ignition. Easy enough to change too.

 

Would an odd fire take the same control module as an even fire??:?

 

Yup. The module just controls spark based on the inputs. The inputs are what is different between the odd fire and even fire.

 

Thanks Sparky, I should have been more specific. You want the 4 pin iirc, definitely not the 7 pin.