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I think I know the answer here, but am posting in case someone else runs into this problem. I searched the older threads and didn't come up with an exact match.

As noted in another thread, I did the M151 into M38a1 electronic ignition conversion. At the same time, I replaced my 12v rewound stock starter with a good used 24v one I bought at the rally this weekend.

The engine turned over fine and she started right up - surprising to me. I went to the engine compartment to fine tune the distributor and my hand touched the rag I had covering the starter terminals. I thought that was weird, so I removed the rag and touched the battery cable. It was hot! I thought about it for a few seconds and touched it again - it was hotter! I hurriedly closed the hood and removed the battery cable before I had a meltdown. After a few minutes I decided to remove the battery cable to prepare to take the switch apart. When I touched the nut on the stud to remove it, it burnt my hand!

Today I am going to remove the switch - I am guessing that the insulators are burnt up inside and the plunger is shorting out.

All I did before the install was to clean the starter with brake cleaner and paint it - I should have checked the switch.

Does this sound like a reasonable guess?

Yes and the corroded, overheated and burned contact issues with that switch have been hashed over several times. It's a common problem and is usually detected when someone starts troubleshooting a battery running down when parked issue. The early M38 starter switch still has NOS Army kits in the vendor system. The later M38 & M38A1 switches have a tougher time finding new parts but most internal damage is repairable.

Thanks Wes. I saw in a previous trhead that you can get a sheet of insulator material from Grainger fairly cheap also - if it is burned up. Hopefully I will be getting out to the shop shortly to remove the switch for inspection. I will take some pics and post what I find.

I also noted a decent spark when I hooked the battery cable back up after installation, indicating current draw. I had a small spark before I changed starters, but this one was about 3 times bigger.

Disconnecting battery before working on the electrics is always a good idea. Should always disconnect negative first and connect negative cable last.

A simple test when you are through is when re-connecting the negative cable last try connecting a test lamp between it and the battery first. If the lamp glows you have a current drain somewhere which may be a switch on or a component or switch that is damaged.

Yep, I pulled the switch off and there were a few things going on in there.

There was some corrosion in one corner starting at the screw. This is also the corner where one of the insulators was burned up.

There was carbon all over the inside of the switch.

One of the contacts was slightly burnt.



I took everything apart and cleaned the housing up using a small screwdriver mainly. All of the parts that I took off were cleaned with the wire wheel on the grinder. I had a good insulator in my 12v starter switch to replace the burnt one in the 24v starter.



There was carbon all over the plunger housing also. I used a small flat screwdriver to scrape as much out as I could and then blew it out with air.

I put it all back together and hooked up the negative cable to the battery - no spark AT ALL! I hit the starter pedal and she worked just fine. I felt the battery cable at the starter connection at it was COOL this time. I proceeded to hook up the timing light and adjusted the distributor, idle and mixture. I do believe that the M151 rotor will need to be cut if I can find out how to do it - she runs better than before, but not perfect!