This is my first post so please bear with me. I have a 1991 Z28 with the 350 TBI. I just bought it and here is what I have done. Replaced ignition with Mallory coil, ignition distributor and rotor. New plug wires. When I jump on it it accelerates very quickly to 4,500 RMP then hangs there. Will not go above it and does not shift until I back off on the trottle. It does the same when in park and N. RPM's stop at 4,500 and will not climb. Like a REV limiter or something is stopping it. We have set the timing and it was retarded to -4 and after we set it it is alot faster now but still wont go above 4,500 rmp's Any suggestions on where to go next?

 

What does it do at 4500RPM? Break up? Sounds like the timing chain may have slipped a tooth or so.

 

It just holds, very constant and deliberate. Like a limiter does not think its in gear or something

 

Have someone push the pedal to the floor with the car off. And watch the throttle body, make sure it's opening all the way and check the tension on the throttle cable.

 

Maybe get the engine pressure tested. My 305 did that and it was just losing compression in the top and bottom end. For me though it revved pretty normally in neutral. How many miles does the engine have on it?

 

Is the tach reading accurately? A known issue with these cars.

4500 "wall" with no popping/break-up under any conditions (loaded or unloaded) is damned near impossible. Ignition problems, weak valve springs, inadequate fuel systems- all would almost certainly have some sort of nasty noises as they reached their RPM limits and caused the power loss and misfire in the upper RPMs.