HEI problems killing modules

[nischev]

Wondering if anyone can help with my truck. Have tried 2 different types of electronic ignition (procomp seperate module system and now hei all in 1 unit) and I keep blowing modules up. When ever I test the system it has a good 13v going to the unit but will be driving along and truck suddenly comes to a halt, replace module and fine again.
Getting a bit expensive to keep going by trial and error so any ideas greatly appreciated.

It is an Mq patrol with 327 chev

[murcod]

Have you got the right type of coil hanging off it? Is the distributor input signal compatible with the modules?

[nischev]

The latest one is one with the coil in the cap. Previous one was all procomp coil etc sold as matching set
says to just hook 12v up and away you go. I wish.

[chimpboy]

Is it in an area where it gets very hot? It's probably not likely but I have heard of these failing when they get too hot.

Another option - does it have a ground connection? I am not sure if all HEI modules have this but the ones I've seen (GM, Jag) have to be grounded to work; if you had a bad ground it could cook it... maybe.



Jason

[Lux308]

what about water? i washed my truck one day,,,, and shorted mine out.
i think it was already stuffed too from the engine heat.. use to over heat.

[nischev]

There is no place to fit a seperate earth it earths through the body of the dissy. there is a fair bit of room around it and only had been driven for about 10 mins.

[nischev]

It is all dry in there.
Keep the suggestions coming they are all things to check.
thanks

[greenfourby]

Get a cheap volt/temp meter from Jaycar and monitor the voltage as you are driving along. Maybe your regulator is stuffed and spiking voltage into the coil

[-Scott-]

Instructions for these things normally tell you to never run the engine with a plug lead disconnected; something about spark having nowhere to go causing abnormally large voltages, which then do nasty things. Personally, I would have thought a lead shorted to ground would do nasty things.

Double check all your plugs and leads. Make sure the leads have good contact to the plug and to the cap. Don't forget the lead from coil to dizzy cap (in your photo) - some people seem to forget it.

Are you sure you've got the correct rotor? I had the wrong one in a dizzy, so it wasn't pointing in the right direction when the spark fired - caused problems for a while.

Silly question: it is killing the modules? It's not a dodgy connection which gets "made" properly when you replace the module?

Earthing through the dizzy, you say. Is the engine properly earthed back to the battery?

Good luck,

Scott

[bilby]

Earthing through the dizzy, you say. Is the engine properly earthed back to the battery?

Good luck,

Scott

not likely by the looks of the photo , seems earthed thru the inlet manifold
id be moving that earth directly to the block

my 2c