Power loss at mid to high rpm

[psuautotechstudent]

So I bought a 68 chevy with a 250 I6 this summer. I've noticed when I drive under heavy acceleration I get a popping from the exhaust that coincides with power loss. It happens at about 3 or 4 grand (estimate, no tach). I recently cut off the exhaust behind the cab and put a glass pack on. I want to say I could notice it before that, but the exhaust makes it much more noticeable. I have an HEI dizzy on the way and plan on replacing plugs and wires and of course setting the timing. Think that will make a difference? Anything else I should check? Thanks for any Help

[Sinister]

I had a problem like that after pressure washing my motor. 350 with points. Tried new points, cap, rotor. Ended up swapping to an HEI, problem solved.

[mclairmo]

Replace fuel filter, too, just to make sure.

[piecesparts]

Thought of the day "Popping noise under heavy acceleration"


Possible valve float issue. Your springs are not strong wnough to keep the valves seated under heavy work loads. Result is damaged valves and pistons, due to spring failure.

[Wrenchbender Ret]

The HEI & new plugs will solve any ignition problems. I would pull the valve cover & make sure all the valves are opening about the same height. It could have a lobe wore down on the camshaft.

[Ricks' 72C10]

Check your intake manifold for air leaks

I ran one for years and had that problem sometimes

[TCLARK]

HEI should solve it................Bad coil or coil wire !

[psuautotechstudent]

So it sounds like once I get the HEI in and everything installed we will find out! I'm hoping it will have an effect on my gas mileage too. I'm a college student and can't afford 20 bucks a week. I sure appreciate the help!

[mclairmo]

Skip White sells a cheap HEI on Ebay that most here have had good luck with.

[piecesparts]

Originally Posted by psuautotechstudent

So it sounds like once I get the HEI in and everything installed we will find out! I'm hoping it will have an effect on my gas mileage too. I'm a college student and can't afford 20 bucks a week. I sure appreciate the help!

Man, I thought that college taught you guys better than that. #1---If you get the truck to run better, you will drive harder, #2 -- If you drive harder, the gas mileage will go down. #3--- Don't you know that the gas in SE Kansas is different that anywhere else? It takes twice the molecules to make something run down there in Pittsburgh than it does in my area--- LOL. Once you get North of Frontenac it starts to lean out some.

[psuautotechstudent]

HAHA! Yeah no kidding! Looks like I'm going to have to find a job to support my gas consumption and my need to buy more parts. And yeah it's something about the air down here in SEK that makes em' run rich. I've heard rumors that it's due to the barometric pressure causes our feet to be a little more heavy, which causes us to push a little too hard on the gas pedal. Hopefully I'll get the job that I'm applying for in Olathe so my truck will lean out a little. LOL