engine knock

ok, so tonight me and my friend took out his 79 vette. he wanted to get a bigger air filter, so we bought one of those and then went and installed it. well we start it up and take it around the block a few times, had a cop tell us to slow down hehe. and we get back turn off the vette get out and talk for a few minutes, turn it back on and start to here this metallic ping in the engine bay, i just looked at him sadly. and he was like, is that frick engine knock, so we hurried and popped the hood. i was like, its just the air filter, put the old one back on. so we did that but it kept doin the knock noise. and it did it the whole way home, and it was freakin loud, i could hear it over my flows on my car and his straight headers on his. pretty loud id say. so basically what i was wanting to know is what he should do. he wants to drop a new engine into it. what are your guyses suggestions?

Just have him run some octane booster in every tank now maybe. I wouldn't go to extremes of putting a new engine in there if the octane booster were to work.

putting a new engine into is not an extreme for him. the l82 sucks. and this is a great way to bump up the power.

Well it's a bit of an extreme compared to adding octane booster every tank for a couple a bucks. And if it's no problem for him and he's looking for more power then of course, do an engine swap.

If it sounds like a little man in there with a big hammer then it probably spun a rod bearing. Octane boost will only help if is preignition clatter. Liquid Fonzie can only fix so much.
Make sure none of the pulleys are rattling and if it's an automatic, check the converter bolts and make sure all 3 are tight (there should be 3, some heavy duty applications have 6).
If it's affordable, there are some cool crate motors out there that are pretty impressive, and they do come w/warranties.
---TEX---

yes, crate motors, thats what im talking about. 380 horsepower right out of a box!!! woohoo.