Ok I have an 86 firebird. It has a 350 from a 1979 chevy van. I have the aluminum intake from the original 305 H.O. It has the stock HEI dizzy with vaccum advance, a non computer controlled quadrajet.

Here's the problem: When my car gets to about 4500 rpms it begins to sputter and if I don't let off the gas it'll nearly die. I thought maybe the fuel pump wasn't performing properly so I replaced it with a 80 gph holley. I installed a clear inline filter to the carb. When I start the car the filter fills up and it runs fine. Then when I get it out and get it on the open road and stomp on it after the first couple of times the rpms get around 4000-4500 and the motor starts to cut out and if I don't let off it'll nearly die. I check the filter and it's about empty. I took the filter out of the carb and I'm just using the inline. Thanks

 

First, it sounds as if the pump is not providing adequate volume at that RPM. That could be due to a delivery volume problem, failing checks in the pump that can no longer provide fuel at that RPM, or a floating pump push rod (weak pump spring) that does not stroke the pump adequately at that RPM.

Second, that is about the same RPM that the factory valve train can start to float the valves, so power loss is not unusual.

 

I have a new holley fuel pump and I'm on another message board and we all are thinking it's valve float. I'm not completely sold on it. I guess I just don't see why it would completely stall the motor unless I let off the gas. I have new fuel line to run and we'll see if that doesn't take care of it.