HELP! 350 Chevy popping out tailpipe at high RPM

Does it get worse when you have the headlights on? BTDT, swapped the alternator for one with an internal regulator and cured it.

 

I don't know, I'll try it. Thanks

 

Cheap plug wires too close to manifold/headers won't last 200 miles. Buy the best plug wires you can find.

HEI with fouled plugs will do that too. Check your plugs after each trial and error or it will drive you nuts.

 

Check the resistance of each plug wire, you can get a cheap meter from harbor freight or radio shack. Check the voltage to the coil. I have had bad condenser cause all kinds weird trouble, they don't seem as well made as they used to be, beware of using really old ones, the electrolite can dry out with age.

 

Had a 69 camaro that did that. Turned out to be a bad coil wire. (point type ignition)

 

You nailed it, it's the alternator. I checked the plugs, and wires, they looked good. I adjusted the valves, no change. I set the dwell, no change. I swapped the carb, no change. I swapped the coil, no change. I swapped the distributer, no change. It actually ran worse when I swapped the distributer, and the coil. All of the above stuff I wanted to do anyway, so it's no great lose. So I'm standing there after changing the distributer, and coil, and now it's popping as I rev it up in the garage. So I pull the plug on the alternator, rev it up, and damn, it's not popping. So I take it for a drive and it runs great! It runs like a stripped *** ape. I called the guy at the alt. shop and told him about it, he had never heard of the alt. doing that. So I know what it is now. I'll get an alt. tomorrow. Thanks guys for all your advise. Dean

 

proof would be plugging it back in and seeing how it runs.....
i see a bit of late mdel sh-tuff that don't like a lot of ac in the system but never a point type.
learn something new everyday!

 

Could be either the alternator or voltage regulator. It's a prime time to update. Later model GM alternators will bolt on, and minor wiring changes will let it work.

Higher RPM's require more voltage for the ignition system. When it gets worse with the lights on, it's a dead giveaway that it's charging, not carb or ignition.

Like people always say, check the easy stuff first. Not much easier than checking the charging system...

 

I have, on my '68 Chevy pickup. It took me a while to track it down. First time I drove it at night told me exactly what the problem was. I swapped out the alternator for an 80 amp one from a Buick I had. I pulled the complete under hood wiring harness from the fuse block on and sat down in the living room with several rolls of wire and new terminals from Napa. Went out and plugged in the new harness and never had another issue with it.

 

My alternator charges when I plug it in. 14.5 volts. It's a 3 wire GM alternator. I might just do a 1 wire and be done with it. The guy at the electrical shop suggested a wiring change to try before I swap it out, so I'll try it tomorrow.