Igntion upgrade help needed.

Igntion upgrade help needed.

dave123

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Location
Florida
Vehicle(s)
1975 CJ5
I have a 75 CJ5 with the 304. It came with a prestolite ignition. I upgraded it to the team rush, which uses the following parts:

79 AMC distributer from a 304
88 ford cap, cap adapter, rotor, wires
79 GM ignition module.

See picture (copied from teamrush.com)

Originally, I used the prestolite wiring. It started and seemed to run fine. I let it run about 15 minutes. Then I got a case of "do it right" and I took out the prestolite wires (35 years old and corroded) and went with the custom wiring. Now, after about 2 minuts of driving, the engine starts sputtering and eventually dies. The module heat sink gets SUPER hot. I have replaced the module and tested the coil, no luck. I have double checked the wiring for problems, it all looks good. I'm stumped. Other facts:


1. the only wires I have are the 5 from the module (1 fender ground, 2 to coil, 2 to dist.) I see a ground on MSD part #8862. I assumed it went nowhere and was not needed. Am I wrong?

2. I assumed dist. was self grounding, do I need a ground there?

3. I ran all the wires (except the ground) next to each other, do I have to separate them?

4. I used 14 gauge wire throughout, ok?

5. I notice a (very) little jumping in my factory voltmeter that I do not remember seeing before, could this be related?

6. Does it matter exactly where I splice my hot to the coil into the hot from the ignition and the voltage regulator? I just have them all hooked together.

Something happened between when it ran fine with the prestolite and when I decided to "do it better" and gut the existing wires and go custom, but for the life of me, I can't figure out what it was

Could there have been something that was in the original wires that I removed without realizing?

If anyone can solve this, you willb e on my Christmas Card list forever! I'm going crazy.

thanx
 
I ran a similar setup in mine and it bugged out because the GM 4 pin module would get to warm. I mounted the module to an old computer CPU heat sink, used thermal compund I got at radio shack between the module and heat sink. Then mounted the whole heatsink and module to the firewall. Ran like a champ after that with no issues.
 
Might find useful info here:
http://www.jeepz.com/forum/engine/16904-tfi-ignition-upgrade.html

Check these diagrams:

heidiagram.jpg


hei_tfi.jpg
 
Last edited:
I ran a similar setup in mine and it bugged out because the GM 4 pin module would get to warm. I mounted the module to an old computer CPU heat sink, used thermal compund I got at radio shack between the module and heat sink. Then mounted the whole heatsink and module to the firewall. Ran like a champ after that with no issues.

Thanx, here is a pic of my current heat sink. I used the compound. Do you think this big enough? What exactly did yours do when it "bugged out". Mine runs great for about 2 minutes, then the engine dies and the heat sink is too hot to touch.

Thanx for the wiring diagram. I grounded to the prestolite ground at the fender, I think I will try straight to the battery like in the diagram.
 
Wait it's inside of a box?
On mine the heat sink was mounted to the firewall and the module to the heat sink.
Out in the open air, it needs plenty of air.
If your worried about it getting wet mount it inside the jeep.
 
Yes in a box.

How big is your heat sink? How hot does it get?

I put a new ground and tried it. I shut the Jeep off when it got too hot to touch.

Do you have a picture?
 
Have a picture at the house but I used this heat sink:

5part.jpg


I stopped by a local computer place and asked if they had any old junk CPU heat sinks I could have for use in my jeep. And explained further what it was for.
They gave me a heatsink and it had the fan. Just for giggles I later wired the fan to come on when the jeep was on, LOL. But ran fine without the fan.
 
Well, I got the biggest honkin heat sink I could find from a friend that builds computers, a big (stupid looking, I know) box.

Drove it for 20 minutes, the box got warm, but not really hot. Jeep ran great. Wow, this was a learning project! 2 hours projected, 2 weeks actual. Ended up buying 2 boxes, 2 coils and 2 modules. I should work for the government.

Thanx for the advice.

One thing, I got some popping in my exhaust that I did not have before. Only when shifting and engine braking. It's not real bad. I'm thinking maybe because I gapped it so wide that I have some unburned fuel?

Here are a couple pics. The one one the fender was the "static test run" and shows the heat sink. The other is finished minus the silicone sealer around the top.
 
If this is good, it’s good but I think I would have the module inside the box and the heat sink outside. With no air circulation it is going to catch up to you eventually. :cool:

Well, I got the biggest honkin heat sink I could find from a friend that builds computers, a big (stupid looking, I know) box.



Drove it for 20 minutes, the box got warm, but not really hot. Jeep ran great. Wow, this was a learning project! 2 hours projected, 2 weeks actual. Ended up buying 2 boxes, 2 coils and 2 modules. I should work for the government.

Thanx for the advice.

One thing, I got some popping in my exhaust that I did not have before. Only when shifting and engine braking. It's not real bad. I'm thinking maybe because I gapped it so wide that I have some unburned fuel?

Here are a couple pics. The one one the fender was the "static test run" and shows the heat sink. The other is finished minus the silicone sealer around the top.
 
if you want the best possible heat transfer to the heat sink goto radioshack and pick up a little tube of as5 thermal paste itll do the job. you could leave that heatsink in the box if you added a small cooling fan and some vent holes, but it would defeat the purpose of it if you put it in there to be waterproof. if thats the case i'd move to the inside of the cab
 
Now you guys got me wondering. I thought the giant heatsink was such overkill that inside would be ok. I got it away from the exhaust as well. I drove it 20 minutes and it did not get more than comfortably warm. I wanted to keep the elements off the module, and the heatisink on the outside would not fit because it was soo big. I think I will keep a close eye on it. I have the spare module that I had thought to be bad and tools, so I probably won't get stranded.

The box has 3 knockouts on each side...
Thanx cheapJeep, that's what I used!
 
I'm thinking of just going to a Pertronix Igniter module for my 79 CJ7 with a 304, because they're extremely simple and they're bullet proof as long as the coil has at least 1.5 ohms resistance or a ballast resistor installed. The only problem is I haven't been able to find a Pertronix part number for this conversion. I keep finding the old 1974 points distributor kits but not the newer electronic ignition kits?????

If not, I might just find an old point style distributor for a 304.

Are there any other motors besides an AMC V8 that I can get one of these old distributors from?
 
Update. This upgrade really helped my MPG. Couple tanks, and I'm getting over 13 MPG, was about 10.5 before.

Heat sink working great, no heat issues.
 
update. My MPG has went up from about 10.5 to over 13. This upgrade should pay for itself.
 
I totally changed my plans. I sold the 304 and bought a 258 that I've now rebuilt.

I decided to go with a GM HEI distributor out of a 250 inline 6 cylinder chevy but with the backward cut gear so it'll work in the AMC 258, but I ran across a great deal on ebay for a brand new HEI that is already set up for the AMC and comes with everything including the cap rotor and coil for only $59 with free shipping!!!!!

I received it just 3 days after I ordered it and couldn't believe what a great deal it was! :D
 
May not be as great a deal as it seems but only time will tell.

LOL yea you usually get what you pay for. The cheap e-bay hei's have a bad reputation. Good luck.
 
LOL yea you usually get what you pay for. The cheap e-bay hei's have a bad reputation. Good luck.

I thought of that, but worst case, maybe the module or coil won't hold up. I can replace either of those for little or nothing. I've never heard of the hard parts failing.
 
Keep us updated. ;)
I thought of that, but worst case, maybe the module or coil won't hold up. I can replace either of those for little or nothing. I've never heard of the hard parts failing.
 

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