Stupid HEI questions

[CPNE]

What gauge wire should be run from 12 volt source to HEI Battery terminal?

Will too large a wire "fry" the unit?

What gets "fried" and is it a replacable part?

Oh and one guess why I'm asking

[Bernie]

Jeff, Too big a wire won't do any harm. I used a #10 wire with a fuse. Could have used a smaller one. If you have too much current going through a small wire the wire will fry. That's how fuses work.

[Yellow Cheyenne]

I ran a 12 gauge wire, which is probably plenty. Too large a wire will never damage anything. If you use too small of a wire, that is when you will get into trouble. If the wire is too small, it will drop voltage and may cause reduced spark and may be hard on the module. I don't think I would use anything under 14 gauge. Use 12 to be safe-I think that is what the factory HEI's use.

Randy

[JimKshortstep4x4]

Jeff,

My guess is that you hooked the power to the tach connector and it would probably fry the module and possibly the pick up coil.
Both items can be changed.

As others have suggested go with #10 or #12 wire. You want a full 12 volts to the distributor.

Let us know when you get it started.

Jim

[MJN]

I used the distributor wire from a '78 harness and used that. The only problem I had was the end in the fuse block was too big for the '72 so I had to get a different one. If you run HEI with the factory points wire, the small wire ( I think it's yellow) will starve the HEI module of power and the module will overheat and fry. I had that happen about three times before I replaced the wire. Depending on what module you have or replace it with they can get expensive. If and when you replace the module always be sure to put the white grease that comes with the new one on the pad in the distributor, this will help dissapate heat and make your module live longer. Hope this helps

[CPNE]

Okay, I'll let you in on why I asked. This is the rebuilt BB just installed and never run.

1. We installed a used HEI with all new parts in the cap part of the unit and we used the dialectic grease on the disk. Everything below the rotor is used factory stuff. We ran an unknown gauge wire to BATT terminal on HEI. here was juice to the HEI, but no spark.

2. We then grabbed another HEI (known good) and installed it with the same guage wire and cap/internals used on first HEI. truck started and ran fine. After we shut it off, we could not start it again. Same scenario as above, juice to HEI, but no spark.

3. We then grabbed a 3rd HEI out of a running truck and installed it. We used cap/internals used on first HEI (the new stuff) BUT we used a smaller diameter wire robbed from running truck. truck started right up and has not exhibited a problem since.

So, the constant between 1, 2 and 3 is the cap and internals (all brand new NAPA parts). These parts must be good as truck now runs. The difference is the 12V source wire and the lower part of the HEI (metal and electronic parts below rotor). I'd be willing to say we had 2 bad HEI's had the truck never started and ran under scenerio #2, but it did until shut off. The difference to me seems to be the 12V source wire but you guys don't seem to think a larger diameter wire could hurt the unit. Any other ideas?

[cheyenne10]

Jeff;

I'm sure you thought about this but were all the wire connections checked three times (as opposed to the standard twice)?

I'm jealous of the new 402!!

[CPNE]

Yes, yes, and yes

[JimKshortstep4x4]

Jeff,

The wire size would have nothing to do with your problem. It is better to go with the #10 or #12 wire size.

Jim