Learn me HEI

Here is the problem. I have an 86 3/4 ton chev 4/4 truck. It had a 305 V8 and an HEI with a four pin module. Out with old in with the new. The new motor is a 350 (age unknown) with an HEI with a 5 pin module. The left side of the two modules are the same two pin reading B and C. The right side of the four pin reads G and W and the Five pin reads from the outside in H L D. From the H L D side there is an interem plug with 2 wires that go to the reluctor just like the four pin. Plugged into that plug is another with 3 wires that has a ground and then splits into 4 wires the exit the dissy with a flat 4 round pin plug. There is nothing from the truck to plug this into. Question: If I unplug this extra pigtail will the truck still start? Or, will I have to change over to a 4 pin module? Or, will I have to change to a different dissy. Went to the Chev dealer and talked to two techs. They said their memory didn't work that far in the past. hmmm----help

http://www.msextra.com/forums/viewtopic.php?f=71&t=15997 http://chevellestuff.net/tech/hei.htm http://forums.hotrod.com/70/6446085/pit-stop/hei-modules/index.html

I love me some google!

Im cornfused why you're not just pulling the dizzy out of the engine getting removed and putting it into the engine getting installed. That way you have a dizzy that matches the original wiring harness. KISS

Bryce

Bingo, just use the dizzy from the 305.

In reply to 81cpcamaro:

The engine is in the truck and the dissy is the large version and it looks like there is going to be a bit of a clearance problem thats why this looked like the easy way. If I had checked it when the engine was out it would have been a not brainer----

viking wrote: In reply to 81cpcamaro: The engine is in the truck and the dissy is the large version and it looks like there is going to be a bit of a clearance problem thats why this looked like the easy way. If I had checked it when the engine was out it would have been a not brainer----

What?

350 vs 305, the distributor should be in exactly the same place as before. If the old one fit in the car in the old motor, it will fit there with the new motor.

In reply to tuna55:

Yes it is in the same place. It looks like there is going to be a firewall clearance problem when taking it out.

Does anyone have any answers on the modules???

The 5th pin is for a knock sensor.

According to the googles, you should be able to swap the modules.

In reply to Toyman01:

Nashco posted the same links I found in the first reply.

not enough room to remove an HEI distributor in a mid 80's GM truck?

there's a ton of room to get the distributor in and out.

if the 86 distributor has a vacuum advance can on it, then that's the one you want to use. they quit using vacuum and mechanical advance in the cars in 81 or so, but trucks still had it until 86, i think.

it's way better than letting the computer control it, and if your truck originally had the vacuum advance can and mechanical advance in the distributor, then the computer probably won't control the timing at all and you will be wondering why it either has no power or pings and rattles like crazy..

novaderrik wrote: not enough room to remove an HEI distributor in a mid 80's GM truck? there's a ton of room to get the distributor in and out.

yup