Ok, the motor is relatively new, just removed ECM, and CFI system. Put on new carb, HEI, and all the other stuff for the switchover. I was having issues with the sending unit for the oil pressure, so I installed a after market gauge, and all seemed to be fine. I would start it cold, and the oil pressure would 50ish, and come down when it warmed up to 25-40 depending on idle or driving. Now yesterday the oil pressure seems to have dropped really low, and I was getting a knock out of it. This morning I went out and was going to do some troubleshooting. I started it up, oil pressure came up to ~40, no knocking, all seemed fine. It has 10/30 in it now. Should I go to a heavier oil, is something else the problem? I'm hoping to get some feedback, I really don't want to swap the motor again... Thanks!

 

If it was knocking & low on pressure I'd really look into it. I'd take a look at the oil pick up tube for looseness & that the pick up has around 3/8" clearence from the bottom of the pan.
Also make sure the distributor oil channel is clean & the widest section is at the oil passage in the block.

 

Sorry to hear that.

If it's knocking and low on oil pressure, doesn't matter what you pour in, even sawdust. (yes it's been done) The motor is smoked.

Pull the dipstick and wipe the oil onto a clean white tissue and let it spread out for a few minutes and look at it under a strong light. If you see glitter, then your answer is instantly clear.

Quit running it and face up to the reality, before it gets any worse than it is.

Sometimes that enthusiastic and thorough "take it to the limit" test driving after a significant mod is .... just a little more than some poor old already wore-out old short block can withstand. Or even, one that wasn't too terribly wore out to begin with.