Rod knock? (Watch video at post #6)

[PolishedTurd]

Ok will do. Thank you!

 

[Spike Morelli]

Let me throw in my two cents here. I build engines for a living, and, I own a '71 with a 351c, so I have personal knowledge of all of this. Yes, by all means drop the pan and check your rod bearings. This will require removing the long front to rear motor mount bolts and lifting the engine up slightly so the pan will come down and clear things like frame crossmember and steering linkage. With any luck, only the rod bearing inserts took the damage, but be ready to encounter a wiped crank rod throw should it have gone further. If a bearing is all it is, just remember, you're still not out of the woods. Make sure you take the oil pan to a shop and have it totally cleaned. Your oil pump has likely ingested some crap too. I recommend a new pump and pick-up screen at this time. Take the time to do it right. If you are running a Holley carb, and backfired the snot out of it, as you said, the power valve will likely be blown out of it, which will cause the carb to now run too rich because it's leaking too much fuel into the metering system. Although the new Holleys say they have "blowout valve protection", I' d check this. New power valves are inexpensive.