Keep Frying HEI Coils PLEASE HELP!

[olnick]

Put a dwell meter on and I'll bet that the dwell is at MAX all the time. (dwell should change with RPM) Yes it will run however it will cook the coil quicker than you can say "oh ****"!!

Olnick

 

[AuroraGirl]

Put a dwell meter on and I'll bet that the dwell is at MAX all the time. (dwell should change with RPM) Yes it will run however it will cook the coil quicker than you can say "oh ****"!!

Olnick

i thought dwell was points only?

 

[potent rodent]

make sure the black ground wire is is also connected to the inner ground strap

 

[Bextreme04]

i thought dwell was points only?

No, dwell is in all ignition types. It is the length of time that the coil is charging. All coils need to charge. In a points system, the dwell is set mechanically using the points. In an HEI system, the ignition module is automatically determining the correct dwell. If the module is bad, you can have crazy dwells(either too short which gives not enough spark energy or too long which can overheat the coil)

 

[82sbshortbed]

I wouldn't dwell on it. He got it fixed.

 

[MikeB]

My coil was acting up and since the dizzy was 40 years old I checked the shaft freeplay and it was too badly worn to just do a coil.I put in a msd streetfire distributor,came complete and popped it in and for about the last 5 years it runs great.$175 at Summit.

Very good idea. The MSD Streetfire is light years better than the low-end cheapies. Also, a GM 93440806 doesn't cost too much and works well. It probably has a bit too much vacuum advance, but that can be modified. in 25+ years I have used both of these as well as Accel and stock distributors. None has every failed me.

 

[MikeB]

As far as voltage, it was a couple of days ago. But if I remember correctly, I was at like 14.3 volts with the old alternator (running at high idle). That seemed on the high side for me, so I removed it and took it to the store. I replaced the alternator with a new one and the guy at the parts store tested both the old and New alternators. Both tested fine, but the old one sounded funny. Like it sounded like a piece of sand or small particle was loose inside the alternator. So I replaced it anyway just to be on the safe side.

Alternator output voltage is regulated at around 14.2 volts. However, with the path the current must take to get to the coil (bulkhead connector, ignition switch, bulkhead connector again), you might find anywhere from 12.0-13.5 volts at the coil. I've seen less than 11 volts on old cars with worn-out switches and connectors.

Glad you got it fixed. Hope it runs well for a long time!

 

[AuroraGirl]

No, dwell is in all ignition types. It is the length of time that the coil is charging. All coils need to charge. In a points system, the dwell is set mechanically using the points. In an HEI system, the ignition module is automatically determining the correct dwell. If the module is bad, you can have crazy dwells(either too short which gives not enough spark energy or too long which can overheat the coil)

why thank you for the explanation!!!! I do appreciate it best not to dwell like the eagle man says

 

[usnrcwo]

Morning, I am having the same problem. Does anyone have a diagram or photos showing where all the grounding wires should be. I haven't thoroughly checked the ones I know about yet but will be doing that this weekend as I fried another rotor/button. I'm particularly curious about the frame to body ground as I don't recall noticing one anywhere unless its there and I didn't realize that's what it was.

 

[crpntr78]

I know there's at least one frame to body ground under the bed.

 

[Rusty Nail]

I'd be pretty quick to buy a new distributor , it's much more simple than actually replacing the pickup coil (if you could even find one for sale) and will include a new module.

Good luck.

 

[SirRobyn0]

I know the OP got it fixed, and I'm seeing this late but for anyone that reads this and is interested in knowing, we do quite a bit of work on squares and other older GM vehicles at the shop, this is how we would troubleshoot a problem like this. If the symptom is stalls and won't re-start or re-starts later, something of that nature and it's not a fuel issue. We'd attempt to test the module by looking at dwell, but even if the module passed testing if it looked like it was age old we'd replace it and retest, in the OP's case of a melted coil we'd do module and coil. If after that it still did it we'd replace the entire distributor. We are talking about 40 year old rigs here and after all that time and mileage there are to many what ifs and potential marginal parts, sloppy bearings, worn gear, pick up coil, advance springs. not that all of those things will cause a stall out, but once you have replaced the easy stuff, it's better I think for long term reliability to just replace the distributor. A/C Delco still makes them new, if for some reason we can't get one quick enough Duralast Gold New (not rebuilt!) units from autozone have been great as well.

 

[Octane]

I know the OP got it fixed, and I'm seeing this late but for anyone that reads this and is interested in knowing, we do quite a bit of work on squares and other older GM vehicles at the shop, this is how we would troubleshoot a problem like this. If the symptom is stalls and won't re-start or re-starts later, something of that nature and it's not a fuel issue. We'd attempt to test the module by looking at dwell, but even if the module passed testing if it looked like it was age old we'd replace it and retest, in the OP's case of a melted coil we'd do module and coil. If after that it still did it we'd replace the entire distributor. We are talking about 40 year old rigs here and after all that time and mileage there are to many what ifs and potential marginal parts, sloppy bearings, worn gear, pick up coil, advance springs. not that all of those things will cause a stall out, but once you have replaced the easy stuff, it's better I think for long term reliability to just replace the distributor. A/C Delco still makes them new, if for some reason we can't get one quick enough Duralast Gold New (not rebuilt!) units from autozone have been great as well.

Yeah,and for about $175 bucks I bought a msd distributor. Good deal considering costs of replacing the individual parts and still having a 40yo dist.I've gotten great service from mine.

 

[SirRobyn0]

Yeah,and for about $175 bucks I bought a msd distributor. Good deal considering costs of replacing the individual parts and still having a 40yo dist.I've gotten great service from mine.

The ac delco units are about the same in price. I guess it all depends on your preferances

 

[Madmacs]

I have been through this before , go buy a new Delco distributor , and move on. Problem solved.