H.lights flickered and the complete shutoff
 

I just picked up my first 67/72 C20 a few weeks ago. I've been working on the bodywork mostly and a few regular engine maintenance items. I replaced the spark plugs and changed the oil so far and that's it. The batter was replaced a few months ago and has worked fine until the other day. I didn't have enough charge to turn the engine over but the lights would power up. It would immediately turn over and run fine after jumping (Wednesday) tonight I tried to start and it did crank but there wasn't enough juice to turn over. I again attached the jumpers and I got an immediate turnover and start. I went for a short trip when the head lights went from full lamp to dim then then a few seconds later the lamps went dead and so did the engine. I was lucky enough go get over to the side and someone pulled over to assist. As soon as I connected the jumpers sparks started flying and the wires heated up so I disconnected. I called the wife thinking this guys cables were bad and had her bring mine over. I experienced the same issue, now after having 3 eyes review I know I had the polarity correct. So right now I'm waiting for the tow truck, what additional information can I provide for a better diagnosis?

Jim

Re: H.lights flickered and the complete shutoff
 

Sounds like there's a dead short somewhere. Is your battery secured or just laying in the tray? How is your positive cable routed?? Is it rubbing on anything which might cause a dead short?? Is your alternator charging, or are you just running around on the battery?

-Josh

Re: H.lights flickered and the complete shutoff
 

I agree, dead short.

Look real close at your cable going to the starter and see if it melted against the headers/exhaust. Also, hopefully you have a fusible link. If so, it's probably fried.

Re: H.lights flickered and the complete shutoff
 

What they're saying is you have a short to ground somewhere. I've also heard it called a copper to steel short. Basically you have some power wire bypassing the load in a circuit by touching the frame, engine, or body, and it's going back to the battery.

Shorts to ground can commonly be found anywhere wires are introduced to heat, chaffing, sharp bends, or moisture.

Start with the battery cable. If it's good, check the battery wire that feeds the alternator.

Re: H.lights flickered and the complete shutoff
 

wire heating is no good.. I would say the same hot to ground.. but.if your light are flickering ,dash lights flicker, battery not charging... thats a good indicator for the alternator going bad..

Re: H.lights flickered and the complete shutoff
 

Well only took 10 seconds to see the issue in the light, the positive cable to the starter fused itself to the exhaust header... Anyone have a picture/diagram of the correct routing for this cable?

Thanks for everyone's help!

Jim
https://goo.gl/photos/XpAGWBG21Dm29nSp8

Re: H.lights flickered and the complete shutoff
 

I don't see the picture, but I figured that was the issue. The only thing I can tell you, is to route the cable to keep it away from the exhaust. You can send it through the engine mount if that helps.

Re: H.lights flickered and the complete shutoff
 

Below are a couple pictures that show how GM secured the positive cable on my '69 with a 350. The first picture shows the original cable and attaching hardware. The note reads "Clamp 1 bolts to short vertical part of frame. Clamps 2 and 3 retained by oil pan bolts #2 & #4 from the front". Clips/clamps 2 and 3 are available from Classic Industries http://www.classicindustries.com/shop/search/?q=c2555

The second picture shows the short flipped up part of the frame referenced in the note. It is above and slightly ahead of the engine stand and fuel pump and has a hole in it for the clamp/retaining loop.