TheRuss

Hi Olds friends,

I have another (hopefully) quick electrical question for you eggheads. Last night I noticed a small spark in the engine bay a couple times a minute, seemingly at random. I couldn't pinpoint where it was coming from, but it looked like either from the front-most spark plug area on the drivers side or the back of the alternator (from my vantage point along the driver side fender)...Any thoughts as to what this could be? Could this be a spark arc due to a bad cable, plug gap, or misfire?

Any suggestions on what to do to fix this?

PS - It was dark out when I saw it. I'll see if I can pinpoint where the spark is coming from tonight.

PPS - The car is a 72 Cutlass S.

PPPS- I just replaced the starter and battery cables (but i don't think they're rubbing against anything they shouldn't. I'm thinking it's unrelated. This spark may have been happening for a while...I don't drive it at night that often.

PPPPS - There's also been chattering from the same location for the past few months which I think is an exhaust leak (stock manifolds). It gets louder as I give more gas.

PPPPPS - That's all the PSes.

Thanks,

-Russ

joe_padavano

From your description it sounds like it might be time for new plug wires. Watching for underhood sparks at night is a good way to check.

Lady72nRob71

Eggheads?? (I had to look that one up...)

Do a visual check on all wiring in sight and look for rubbing, cuts, or pinches, particularly plug wires.
If you find no clues, try to pinpoint more where it is coming from, particularly if near a plug wire or coming from the alternator.
If not near a plug wire, try turning on some high current items, too, like heater fan on max speed and see if the spark intensity / frequency is affected. What color is the spark? Blue or orange or white? Is it like a tiny ember that leaps out and falls to the ground or does it jump from one part to another?

TheRuss

Man, you guys are quick!

I'll run these science experiments when it gets dark.

To answer your questions, Rob, it was orangish white if memory serves (is reverse photographic memory a thing?). I thought it looked ember-y, but the last one I saw made a staple shape, so I think it's jumping.

Also, I'm not sure my heater fan runs on full speed. I've problems with that since I got the car, despite replacing the resistor/switch? (little gray box on the firewall). It likes to blow fuses and/or stay on when the car is turned off. But that's a problem for another day hehe. I'll turn on what I have.

A question in response to Joe's post. Do you have any suggestions on what year/make to buy wires for at the auto parts store for an HEI converted (GM stock...probably from the 80s) 350 (I probably should have mentioned it was HEI in the first post)? I know I can cut them myself...but I'd rather just buy them pre-cut if possible because I don't trust myself to measure/cut/route them nicely. hehe.

Thanks again,
- Russ

joe_padavano

Wires for any SBO from 1973-1990 will work. Be careful with the pre-cut wires, however. I've gotten a few sets where the wires didn't always reach correctly. Admittedly, these were low-buck Chinesium wire sets, so some of that is to be expected.