I don't see how it could be fuel delivery problem unless the carb is all junked up, there should be MORE than enough fuel in the bowls to allow the motor to rev up to 3,000 rpm in neutral. I think one time I turned my fuel pump off and the engine kept running at idle for another 5 minutes.

You might not want to hear this, but check the cam timing or valve springs.

or before you check those, tell us what changed right before this problem occured. did you do a cam swap? or did you replace the timing chain/gears? did you change the heads?

instead of just blindly adding shims, pull off your intake and actually look at the lifters to get an idea of how much preload you have in them.


If this is a brand new engine that you're still trying to tune it in, then check the valve springs and check your cam timing. with a degree wheel and a dial indicator, you can check the cam timing and not even remove the timing cover. (but you will have to remove a valve cover to put a dial indicator on #1 intake valve)