1971 Chevy Chevelle Ignition Problem

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1971 CHEVROLET CHEVELLE

Electrical problem
1971 Chevy Chevelle V8 Two Wheel Drive Automatic

1971 Chevelle 350 engine driving me crazy
After running excellent for several years, and am traveling 70 mph downhill such that engine is not pulling or braking, all of a sudden the tach reads 0 rpm, (acted exactly as if I shut the key off, but the CD player didnÃ¢ï¿½ï¿½t miss a lick) the car slows down for about 2 seconds, and then is running smoothly again after a loud backfire. I have driven the car several times since then and the problem is getting worse 30 to 40 of these incidents in 200 miles). Three things seem to be consistent; 1) if I punch the accelerator from 0 to 15 mph (low gear), at approximately 2200 rpm, the engine dies (no electrical power to ignition), and then hits again after 1 or 2 seconds. 2) If going up a fairly steep grade (like on-ramp to an overpass) the engine cuts out unrelated to the rpm and I barely get up the ramp. 3) Going on slight down grade and no load on the engine especially if I am traveling over 65 mph the engine cuts out.
The engine never cuts out for more than 1 or 2 seconds, and if I donÃ¢ï¿½ï¿½t let off the accelerator quickly, I get some really load backfires.
The engine is pretty much original ignition (not electronic). I pulled the tach, to make sure that was not the problem. Been looking for possible short in wiring somewhere. Does anyone have any suggestions? Trying to figure out possible causes.

2 Replies

HMAC300

MECHANIC
48,601 POSTS

It sounds like you are either losing ground to the distributor plate when the advance moves it. Or you may have what is commonly called grounded points. That is very hard to diagnose and you really need to have a mechanic that is familar with a point type set up. You could also have a loosed wire connecting to the points, especially if the wire connection is held by a spring. A few other things to check would be dwell angle, timing, all the normal stuff that is associated with a point type ignition. There should be a small ground wire that connects themovable breaker plate to the side of the distributor.