Whats that noise coming from my 318?

EDIT I posted before you posted video. That sounds to me like a valve problem. Pushrod/ rocker/ valve/ broken spring etc


Start by running the engine when cool or barely warm with all belts removed, for a short time

Use a scrap length of hose, one end to your ear, as a probe. Search all around, exhaust, manifold, flanges, etc. Probe inside valve covers through oil fill

"Up front....." if it gets to that, temporarily pull fuel pump off and run engine briefly