1970 a100 running great then bad then back again, now meltedwires

70k original 318 ran great then started missing and backfiring, points seemed to be going out of adjustment, re-adjusted to .017, ran well again for awhile them started running , missing backfiring but would then start running well again.

Checked wires, vac leaks, fuel, spark... replaced dizzy n intermediate shaft n bushing, coil, alt, start relay, ballast, plugs/wires, starter, 4brrl carb, intake, valve job, fuel filter, exhaust, really good tune up. Ran great, put a good 100 miles on it then started running really rough again, missing, backfiring... after a bit of that is start running well again, did that a couple times then finally limped it off the highway checked some wires, points, timing, in between starting it when it finally burned up the wrote running from the alt to the start relay up the wiring harness toward the dash. Was it a wiring issue the whole time?

Any help would be great as this is driving me insane lol

I would think it was a wiring issue all along.
Wouldn't think any tune up related item failing could cause the wiring to burn up........

I'd start at the bulk head connector (assuming you have one) and pull the connectors off and look for corrosion, loose and over heated terminals.

Check the amp gauge for loose wires or shorted out. Then bypass the amp meter and add a volt meter instead.

So it was probably some ground issue from the start? Arr lol

Not a wiring issue that caused the orig part time misfiringprob but it does have a wiring issue now either full fielding (check charging voltage) or there is a dead short or very high (improper) draw (likely) under the dash that is drawing excessive current & burning the wiring. I must admit this is the most discombobulated symptomology I've ever ran into! If the condensor is still hooked up to the coil (should be on positive side if it is there) I'm gonna go way out on a limb (& K.I.S.S.) & WAG that that is it! Holler back. PS dist/cap/rotor all look good? plugs/plug wires OK? EDIT With more thought I had the exact same prob in '85 & it was the Sears white replacement HEI module (4 in a row!) and recently my coil did somewhat the same thing (but didn't you say you replaced the coil?)

Yeah im totally confused too... I figured hopefully it was some short and since the wires to the ammeter fried quite a few other wires I decided to start with the whole wiring harness. Luckily someone an hour away had a 69 camper harness for 150 so I'm putting that in and doing the bypass. but I'm running into a few hang ups.

A couple wires are different and was wondering if anyone knew what they might go to... here's an image and there are also a couple wire plugs for the brakes that are not on my 70 tradesman and a 2 wire black with white stripes plug under the floor mat near the brake pedal that the 69 harness has no plug for.

Any help would be great as I'm broke and stuck at a friend's out of town in a crazy town called apache junction... it's a little crazy in this town

Shoot I can't attach the photo but in the dash I have an extra light blue wire with an eye end, a pink with black stripe with post plug, darker blue female spade and the only thing extra from my original 70 dash is the orange post for the temp Guage and the white post for the oil pressure Guage. .. thanks yall, I'll try to post the pic later.

the wiring diagrams at www.mymopar.com might help. I've heard they are missing a circuit here and there but I've had excellent luck with their schematics. where exactly is the harness/loom/wire ends at in question?

Most of them are behind the dash at the moment, except the brake wires im still trying to figure out... I found the pink wire attaches to the temp and the dark blue attaches to the emergency flashers but the rest of the flasher wire connectors are missing too, still not sure on the light blue wire with the eye connector at the end?

Thanks for the link but couldn't find the a100 or a diagram with the wires I have from this camper harness. .

You might grab your VOM & start ohming em & see what wires on the other ends are hot. Need jumper wires with alligator clips (I make up several long ones for general work & they would work fine for this) & I always pull a batt cable before I switch the meter to ohms so the only power is coming from the meter battery.

That's really the only way to know unless it's spotted visually. The battery has to be disconnected before ohm checking power wires to ground.

shoot don't think i have access to a meter, broke down out of town and flat broke myself. i'm at a friends so i'll see if he has one.

finally can post some pics... i've since connected the pink to the orange post for the temp, i believe the white wire is for my oil pressure gauge while the replacement harness has just an oil light white and black wires, i think the extra red and white wires down near the brake proportion valve go to the brake light switch under the pedal(must have been in a different location for the camper?

i have no idea where the light blue wire with eye goes behind the dash, no clue where the wires for the flashers are lol??? also there is one less field wire going toward the ballast, will that matter with my dual field alternator?

thanks so much

Ok finally got most of the wires all wired up started the van up and it ran smooth for a couple minutes then back to running rough again. .. seemed like it is missing? Then when I Rev it up runs worse and starts to want to backfire?? I'm going to swap my new coil but I don't know what else to check? ?

Is this motor the original to the A 100? Has it ever had a timing chain installed? Do you have access to a timing light? And, is the timing steady or fluctuating? When its running like crap, shut it off, bring #1 up on compression, pull off the dist cap and see if the rotor is pointing towards #1 plug wire. Also, with the cap off, turn the motor backwards by hand and check to see if the motor will turn a ways before the rotor moves. There should be very little delay when you change the direction the motor was turning before the rotor moves. a delay indicates slop in the timing chain & gears.

Have you cleaned both ends of the negative cable or replaced it? Do you have a good clean block surface the neg cable connects to?

When the motor is running poorly, is there gas in the carb? I've seen a lot of old gas tanks with stuff floating around in them that would float to the fuel pickup and plug it up completely or near completely and cause a poor running condition after a drive. Might also b worth taking the gas cap off and see how it runs, a plugged gas tank vent will mess you up too. Gene

I'm wondering if it has a vac leak that is showing up when it warms up cuz it is leaner then & until then the rich mixture from the choke covers that up.

You say the points need constant adjustment.
Maybe they are burning, instead of wearing out of adjustment.
Did you lubricate them?
Been awhile, but I seem to remember that will happen if the coil is wired backwards.
Would go along with the wiring trouble.
Good luck,
that will be a fun truck once you get it sorted.