99 corvette with knocking noise - idles fine - good oil pres

[mysjet]

Hi, new to site - just got this corvette - trying to find ways to take care of problem - other modifications to car include headers, items set up for racing, sheets of metal underneath floorboard, intake manifold specially done with someone's name on it.

[silverWS6]

Need more details on the noise, is it a big knock? Or a small knock? Does it increase when you rev the engine? Details man details!

[Knight]

Agree, we could use a little better description. It could be something simple like an exhaust leak, to something more complicated.

[Circa307]

i have a knock when i first crank mine up on cold mornings but goes away when it warms up and goes away as i rev it up. is this what yours is doing???

[BlownC5]

could be piston slap too