rico84

1984 c-4 w/cross-fire injection and hyper-tech chip when I jump on it , engine has hard knock like valve or lifter would , but its not. where to look next?

ls777z

Assuming you've ruled out a rod or lifter going bad have you taken a look around the engine bay? Possibly some bracket or bolt has loosened and under acceleration with the twist of the motor something is moving/hitting ?

corvettenorway

check and dobble check timing , pull nr one spark plug and find tds. se if the timing mark on the damper match !

383vett

Does it knock with the stock chip in?

ls777z

Just throwing out another suggestion. What octane fuel are you using?

1984Z51auto

Are you confident that the outer ring on the harmonic damper has not shifted? The rubber can deteriorate over time and miles. Then the ring shifts and the timing mark moves making your static timing off. The ring can also move in or out on the hub. If it moves too far in it will hit the timing cover and knock (bang) on that and if it moves out, it will hit the rotating stuff. Just a thought.

Paul Workman

If it doesn't seem to be tied specifically to RPM, a bad motor mount caused a knocking (more like a clunking) sound on one of my cars (non-Corvette). Just a thought.