hi all, i have been working of my first engine restoration process, mostly cosmetic to be honest, mainly because i don't know all the things I should do during a rebuild... but i think i may have just discovered one.... here is a quick summery. i took it all apart cleaned it replaced some stuff that looked like they need to be replaced, cleaned everything really good, had the heads machined ( they said they looked great) put it back together and painted it.

Before

after
i got it back in the vehicle started it up (first try it started right up and sounded pretty damn good... i was very surprised and confused to be honest haha) i started it a few more time to adjust idle on the cab. all times it sounded good.... then this happened.... <click here to see video> ... First i removed the valve covers to see if there was anything obvious, nothing. then I tried to isolate the noise to a cylinder by pull wires of the distributer... nothing. My guess is a rod bearing (or whatever the bearing at the crankshaft piston rod connection is called) and my second guess is when the engine was out and taken apart i should have replaced those? Just because it doesn't seen to complicated and everything is accessible. anyways I'm just hoping to learn more so i can pretend to be smart around my friends. but for real if anyone can tell what that hard knocking sound is (not the hissing that's because i have some vacuum tubes pulled / i may have broken one trying to get it off...) that would be great! I don't mined pulling the engine again so at least i have that going for me, thanks in advance!

 

ehhh I forgot to mention this... its a 351w from 1977-8 C-6 trans and a 2150 carb

 

How much were the heads milled? Does the knock only occur when the engine is warm?

 

Im not sure how much they milled, i didn't think to ask. and the sound begins as soon as its running.

 

That sounds like a pretty solid knock, did it have oil pressure, did you hear it run before you worked on it, if it is rod bearings, it may be too late for just replacing inserts.

 

pretty solid knock... kind of a bummer... but yes on the oil pressure, and i drove it back from Arizona no knock, and i have had it running a few times since the rebuild/ reinstall before the knocking started. the knocking just started.