Ive got a real strange problem that you guys hopefully can help me out with. After retorquing my cylinder heads, I took the car out for a test drive. The car seemed to run fine until about 3500rpm, at which point it would cut out, drop to about 1000rpm, and sputter badly. I parked the car, then tried to drive it later. Now the engine starts and idles fine, but as soon as the throttle is opened a small bit, the rpms drop and the engine dies. If the throttle is repeatedly tapped lightly, the engine will rev up, but it is very rough and it constantly backfires through the intake.

The fuel pressure is steady, there are no codes stored. I tried a known good coil, no change. The distributor is a new MSD, the inside of the cap is in good shape...no moisture.

The car is an '89 Formula, 355, Topline heads, XR282HR, HSR, etc.

Im at a loss, any help would be much appreciated.

 

check your pushrods and lifters. happened to me once.

one of my pushrods bent so badly it broke. and the exhaust valve wasn't opening. You couldn't hear it backfire throught thre intake at idle or maybe around 3500 is where it started, but as soon as you gave it gas it started back firing and did exactly as you say.

might be a pushrod, might be a badly worn lifter. Cant hurt to check

 

Thanks. Ill check that out.

 

Maybe an over tightened rocker.

 

yeah man, just figure out which one is doing it, it shouldn't be too hard to figure out which header tube is cold. And...... look at that pushrod/rocker to see if they move.