Hey guys, My good friend just did a valve lash adjustment for me, and my valves are still chattery. He did it the right way and even checked his work after i said something. Is this normal for a k20 with 90k on it? It sounds like my buddies with cams. Also every once in a while i get a backfire(2-3 weeks) on a shift, I know that this is unburnt gas, but does this mean something? Anything I can do to make my engine run healthier? Anybody recommend any fluid to add to the engine?

 

I would recheck the valve adjustment. the only reason they would chatter is because they aren't set up right. Unless the head was damaged .