Hi, I recently purchased another camaro for a daily driver. Its a 85 Z28 with the 305 TPI. The car is absolutely mint. Got it dirt cheap too.
Now what I cant figure out is.... the kid I bought it from said he accidently over reved it and the timing chain jumped a tooth due to having a lot of miles on it. It is bone stock untouched. Now he told me that he changed the timing chain and now the engine seems to have a semi-loud clank under the TPI intake. I can even feel it if I rev it to 2k and put my hand on the intake.
I pulled the valve covers off and checked the rockers and all seem nice and snug and functioning normally. The engine runs and idles. At idle you dont hear it much. I have a lot of experiance and build engines for a living, but have never stumbled upon somthing like this. Now I know what a rod knock sounds like and am 200% sure its not a rod knock.
Also I think its not a bent valve cause I watched the valves open and close smoothly. Could it be the cam cracked, or a piston chipped or a lifter missing a piece??
What do you guys think. I know that if the timing chain jumped a tooth, so it is most likely that all the valves smacked the pistons.
Just wanted some input before I tear off the heads and intake. It also has good oil pressure and some times you hear a slight back fire thru intake. At idle its not as bad. When you rev, its noticed. Appreciate it guys. Sorry its so long.

 

ouch, better start some dissassembly just to be sure. better safe than sorry!!

Good luck Bro!!

 

Yeah, I am going to pull the heads this week. Its a shame, such a nice car and nice motor, that guy was such a dumb a$$ for beating on it the way he did. Oh well, now it will get a nice mild cam and roller rockers and springs that I have laying around. Thanks bro.

 

Sounds to me like a broken exhaust valve spring.