i have made a discovery on my IROC. need you guys' help to confirm. when i bought her, she had a slight tick when cold at a certain RPM. it went away when warm. the previous owner (now a good friend, for obvious reasons 8) ) told me it was a rod knock beginning. i was kind of skeptical. well, then coming back from a Camaro/Firebird show my car was in (took 2nd place behind a rare '90 RS Vert in that one) the tick turned into a knock. i was a believer. fast forward to today. a guy who is buying a Toyota off of me who is pretty good with GM's (as am i, but another mind never hurts.) asked if he could have a listen since his friend (who had heard it previously) didn't think it was a rod knock. i said "sure" and fired her up. he revved her up (from underhood) and agreed with his friend, that it was top end coming from the left (driver's side) valvetrain. so i decided to go on a wild goose chase and remove the DS valve cover (hell, its the driver side, it aint that hard!) and looking visually everything looked ok. but then on a hunch of my own, i began to try and wiggle the pushrods. 6 felt tight and i couldn't move them. but two i was able to move and could SIMULATE THE SOUND!! i couldn't make it as loud, but it was the same sound. could this be the problem? could these severely worn out heads (smokes BAD on startup) be causing this faux rod knock? or am i just nutz?

thanks in advance!
Josh

 

The studs that hold the rockers may be pulling out.
You may just need to tighten the rockers.
When does it smoke? Only on startup indicates valve seals.
It's also possible that your cam is cashing in.

 

top to bottom they are tight, they only move slightly side to side. only 2 do this, the other 6 are fine...only two you can get the noise out of.

thanks for the help!
Josh

 

and yea, it only smokes on startup. i know this is valve seals, GM's are so good for that! this is another reason i think the heads are just worn out and in need of replacement (to rebuild them would be sacrelige...)

Josh

 

How many miles are on the engine? If it is the original 89 engine, I seriously doubt it is the cam cashing in since it is a roller cam. However the cam bearings could be wearing.
When you checked the rocker arms, did you keep rotating the crank and check all of them for play? Since all factory heads seem to give the little puff of smoke at start up once they get miles on them I wouldnt worry about that too much. I would just try to adjust all the valves and then if it still makes noise, after that it would seem you have a problem.
Keep us posted!