Hei Distributor

[67-72lover]

Hello I have a 71 chevy c10 with a 350 someone has put a hei dist in the truck prior to me owning it. Ever since ive owned I keep buring through ignition control modules every couple of months. Can any point me in the direction what is causing this please. I was told that the wire coming from the junction block to my distributor originally was a resistor wire needs to be changed over to run 12 volts at all times looks to be changed but am gonna do it again to make sure. Can i just splice as close to the junction block and as close to the connector on the distributor as possible and be safe?

Thanks for the help

[kaycee]

Just run a new wire from the fuse block ,I would not tie into the resistance wire your asking for problems . When you change out module do you use heat sink paste on the bottom of module ?DO NOT USE DIE-ELECTRIC GREASE not the same as heat sink paste

[dmjlambert]

Here is how I replaced the resistor wire. https://67-72chevytrucks.com/vboard/...d.php?t=708975

[StingRay]

Are you using heat sink compound under the module? Delco modules will last the longest. Some of the other aftermarket stuff is 3rd rate. My 69 one ton came to me hooked up to the resistor wire. It never killed a module in all the years it was like that. I did hook it to full voltage myself.

Originally Posted by 67-72lover

Hello I have a 71 chevy c10 with a 350 someone has put a hei dist in the truck prior to me owning it. Ever since ive owned I keep buring through ignition control modules every couple of months. Can any point me in the direction what is causing this please. I was told that the wire coming from the junction block to my distributor originally was a resistor wire needs to be changed over to run 12 volts at all times looks to be changed but am gonna do it again to make sure. Can i just splice as close to the junction block and as close to the connector on the distributor as possible and be safe?

Thanks for the help

[kwmech]

Make sure the coil has the ground strap or ground wire going from the center of the 3 wire connector to the coil. They seem to disappear when people change distributor caps. I do not have a pic, but I bet somebody will throw one up

[Willys_MB]

I had this problem. Pull the dizzy and check the end play and any other specs you can find. Mine was an old ACDelco and it was so worn out. To rebuild it with Echlin parts was going to be $200, so I bought, as a temporary fix, a Chairman Mao special on Amazon for $54 and haven’t looked back. I’ve put ~1,000 miles on it and I’m not having issues anymore.

There are a lot of reasons your module could be burning up. It’s not just the wiring, heat sink compound, hot engine bay, etc. The module is the weak link in the system, so you never know until you check EVERYTHING.

[68 P.O.S.]

Another thing to check is your coil. The epoxy they're set in doesn't dissipate heat, it holds it in. This can cause layer shorting in the coil, which takes out modules.

[67-72lover]

So I tested my wire coming from my junction block on the firewall im getting 11.90 volts thru it. It is a 14 gage wire. Do I need exactly 12 volts or is that about what I'm gonna get? If I need exactly 12 do I need to change the gage wire?

Thanks

[HO455]

You need to check the voltage at the BAT connection on the HEI as the factory wire from the firewall connector is a resistor wire that will drop the voltage even more before it gets to the HEI.
Check the voltage running. 11.9 volts at the HEI would be a bit low, but should be okay.
But the lower voltage in conjunction with another one of the previously mentioned issues could be causing the failures. In addition a failing pickup ring could be causing or contributing to the failures.
Your best course of action would be to take your distributor to someone with a distributor machine and who is versed in troubleshooting HEIs. That way you should be able to pinpoint the failure points and not just change parts hoping that you solve the problem.
A 14 guage wire will be sufficient for the HEI. You may want to check out why your voltage is low at the bulkhead connector. Is there more than a half a volt difference between the battery voltage and the voltage at the connector. If so you need to trace the voltage back to the ignition switch to find where your voltage is dropping at.
Good luck and keep us posted.

[67-72lover]

The 11.9 volt reading im getting is with the key in the on postion not running. If running I should get a higher volt reading through the wire but the control module should adjust the voltage going in correct. So from what im gathering is the 11.9 volt should be fine for the on postion?

[HO455]

The reason to check the voltage at the HEI terminal with the engine running is when the HEI is providing spark its amp draw is at or near maximum.
If you have a poor connection in the wiring to the HEI the voltage being supplied to the HEI will drop. Since you are looking for the cause of repeated failures you are hoping to discover something that is on the nearly out of specification. So you may find that the 11.9 volts you measured with the engine off may be less with the engine running.
I am assuming by control module you mean the voltage regulator in the alternator which only regulates the voltage at the point the alternator sensor wiring is connected to. The sensor wire generally not connected to the ignition wiring directly.

[70STOVEBOLT]

I disagree with the statement that a 14 gauge wire is sufficient. I would run a new 12 gauge wire from the junction block to the distributor. On vehicles that came from the factory with HEI ignition, the wire is 12 gauge.

[sanddunecoon]

Originally Posted by 67-72lover

Hello I have a 71 chevy c10 with a 350 someone has put a hei dist in the truck prior to me owning it. Ever since ive owned I keep buring through ignition control modules every couple of months. Can any point me in the direction what is causing this please. I was told that the wire coming from the junction block to my distributor originally was a resistor wire needs to be changed over to run 12 volts at all times looks to be changed but am gonna do it again to make sure. Can i just splice as close to the junction block and as close to the connector on the distributor as possible and be safe?

Thanks for the help

i had this same problem with my 72 GMC and every damn time i hooked up the factory tach to the tach terminal on the HEI my module would be dead within a week. i made the same mistake over and over because i didnt believe it was that.
i know there are folks that will disagree but it happened like clockwork every time.