I have a 350 in my 86 z28 which is actually, from numbers on the block, a 1999 crate motor. I am new to this car.

When on the gas, I hear a low banging sound that sounds as though it's coming from the top of the engine right up by the firewall. Possibly on the driver side. Almost like one of the cylinders has detonation or something, a timing issue. Not sure.

It only does it when under heavy-ish acceleration. If I am gentle with it, I don't hear it. But if I get on it, the noise and banging becomes prominent enough to shake the whole car.

I have a video uploaded here. You can slightly hear it when I twist the throttle linkage.