Hei conversion troubleshooting

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67Dart273 said:
Easy. Look at your wiring diagram, the ignition switch and bulkhead connector. They normally are called IGN1 and IGN2. The whole deal is, IGN1 is tradtionally "ignition run" and GOES COLD during starting. IGN2 is the coil resistor bypass, often a brown wire, and goes from the igntion switch to the coil+ side of the ballast resistor. It is the ONLY source of igntion voltage during starting, and (normally) supplies the coil during cranking, and "feeds backwards" through the ballast resistor to feed the ECU

If you are bypassing the ballast, those connections must be tied together, then run to feed the ignition system and VR, and on 70/ later cars, the altlernator blue field.

Go to MyMopar and download a service manual I WOULD NOT recomment bypassing the ballast on a Mopar ECU
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Spent this morning converting from ECU to HEI. Regapped the plugs, running like a champ. I bypassed the ballast, but left everything in tact so I can go back to ECU. I will post pics in the next day or two.
 
skidmark said:
Maybe I’m not understanding it all, but
I think electronic ignition didn’t come out till 72?
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It was 72 when the electronic ignition was introduced. That doesn't mean mine was originally that way, but it was in
my duster when I bought it.
 
So, I made the drive down safely, have been daily driving the car and I think I am ready to give HEI a try again. I have replaced the wiring harness, have my HEI harness/relay all soldered up and ready, and a fresh 4-pin ECU. Have gutted an old BR and soldered a 10-guage jumper so I don't have to cut up my wiring harness. I am scared to permanently mod the wiring harness until I am dead sure the HEI will work reliably, since I depend on this car as my daily driver right now. I know the HEI will be rock-solid once I get it running right.

Car is running ok with points but it is very hot down here, coil gets pretty toasty and it still fouls plugs (not terribly, but i'm doing a lot of stop sign driving and idling down here) so its time for HEI.

My theory (fingers crossed) is that my overvoltage condition (fixed, new VR and grounds) and hot/lean running condition (fixed, radiator clean/coolant flush and carb adjustments) was burning up ignition modules. Really hope it works this time.
 
Update: With a brand new 4-pin ECU, I gave the HEI a try yet again. Exact same issue. Starts and idles fantastic, rev to about 2k and it starts spluttering and backfiring severely. Radically (about 15 degrees each way) advanced and retarded timing with same results. Idle and throttle response was affected, of course but the basic issue of not being able to rev past 2k remained.

I decided to finally throw in the towel and get a pertronix conversion (version 1). If it works I will sell my HEI components at a steep discount. I'm really bummed I couldn't get it to work and completely stumped as to why.
 
smokinnjokin said:
Update: With a brand new 4-pin ECU, I gave the HEI a try yet again. Exact same issue. Starts and idles fantastic, rev to about 2k and it starts spluttering and backfiring severely. Radically (about 15 degrees each way) advanced and retarded timing with same results. Idle and throttle response was affected, of course but the basic issue of not being able to rev past 2k remained.

I decided to finally throw in the towel and get a pertronix conversion (version 1). If it works I will sell my HEI components at a steep discount. I'm really bummed I couldn't get it to work and completely stumped as to why.
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The HEI conversion shouldn't have any effect on the timing due to the fact you use the same distributor, it should just giving you a hotter spark (if you went to a high voltage coil) and a bit more reliability. Other than regapping the plugs, there shouldn't be diff with idle and throttle response.
 
GTS Dave said:
The HEI conversion shouldn't have any effect on the timing due to the fact you use the same distributor, it should just giving you a hotter spark (if you went to a high voltage coil) and a bit more reliability. Other than regapping the plugs, there shouldn't be diff with idle and throttle response.
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I did not use the same distributor. It was a conversion from points dist to factory mopar EE distributor with HEI.
 
There are eight pages of help and its still not working any better then day one. Pretty frustrating I must say.
 
smokinnjokin said:
Slapped in a pertronix first gen kit, instant success. All my HEI stuff is now for sale at a discount. [FOR SALE] - Small Block electronic distributors and HEI conversion kit

Thank you all for the help. I think there is some crazy ground gremlin in my car or something, who knows.
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Congrats! I ran a new ground to every mounting bolt/screw on each device in the ignition chain for assurance.
Put a link on here of what you bought so everyone else will know what worked for you. :thumbsup:
 
I hate to bring up an old thread but I'm having this same exact issue with my 4 pin hei swap. It's so frustrating.
 
7dart0 said:
I hate to bring up an old thread but I'm having this same exact issue with my 4 pin hei swap. It's so frustrating.
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Please start a new thread. WAY easier to follow than mixed in with this one.
 
The only thing that I can think of is that my system is continually charging at 14.5 to 15 V due to voltage drop to the regulator supply wire. Next time I try to do the HEI thing, I’m going to install a relay for the VR as well as the one to ignition. My theory is that when it gets too much voltage the GM 4-pin goes into some kind of limp mode.
 
Hate to bring up an old post, but are you guys sure you don't have the distributor to hei module wires reversed?

The car will run, but with sputtering issues. Just an idea...
 
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