Help with knock noise
 

I noticed that on first start ups there's this knock noise I hear. It goes away after a few minutes or as the engine gets warm.

I'm very hesitant to drive it now cause I don't want to cause any more damage if this is in fact rod knock or what ever it is.

Can anyone help ID this noise?

https://www.youtube.com/watch?v=r5GHT7oTeQg

Not sure maybe a Gas knock. How old is the gas? What did you do to the car last, did you mess with the engine or did this just start happining.

Have you checked the valve clearances? Timing chain is usually louder at idle, rod usually sounds deeper, piston slap? Get your stethoscope out and see if you can pinpoint it.

gas is new. tank was cleaned and flushed before i filled it. i've been trying to get my carbs dialed in and i noticed it when i started it in the mornings it would be pretty loud. that video is not at operating temp but is not at a cold start either.

what i noticed is the #6 cylinder's plug is slightly wet and according to my carb float tool it's the weakest of the 6.

Sounds like piston slap and it will go away as the pistons warm up...

You could compare to my knock movie in fourth post
Hopefully your sound is different. In my case cylinder 4 seized, possibly caused by a bore wash

If you have forged pistons (Nikasils) you often hear a knock/slap when cold. Normal. Same thing happens in SB Chevy's too with FP's.
Rod knock does not go away when warmed up.

not sure if the pistons in there are forged. i took it to my wrench and will know a little more later or early tomorrow.

as an aside, anyone know if oil weight has anything to do with this? i put 20/50 (after a complete flush) in it and not sure if thats the same weight the PO used.

If you are playing with the carbs you can make it knock if you get a cylinder too lean. That won't normally go away as the motor warms.

Doesn't sound quite like a rod knock, but could be a piston pin. If I remember, though, the noise of a loose piston pin changes volume aa the engine is accelerated and decelerated. The other suggestions about piston slap and a loose t chain tensioner are also very viable. Stethoscope should help.

valves were too tight and stuck open. compression was at 70 psi and after the valve adjustment it came back to 150 psi.

whew!!