I have an 89 GTA with a 5.7L in it.I bought it back in 1995 with 65,000 miles on it,it was abused,had a mild cam in it,the heads were shot{it smoked oil on startup},it had broken a few valvesprings early on,and it had a nasty clack that got worse as the engine warmed up.It also had a clogged cat,aftermarket exhaust,and aftermarket intake runners.
I took off the heads and had them rebuilt with new guides,gave them a mild port job including a bowl blend,new springs,new stock replacement rocker arms and pushrods.I reassembled the engine and adjusted the valves after it warmed up.The clack was still there.I backed off each rocker arm one at a time and couldnt get the clack to sync up with any of the valves,and all of the valves ran down OK and seem quite.I gutted the cat out before eventually replacing it,I added a stock exhaust system to it,and now almost 10 years later with 101,000 miles on the clock,the engine still clacks.It sometimes sounds like a leaky header gasket{the car has stock manifolds though}.I checked for any leaks around the exhaust crossover nothing seems to be leaking.I dropped one cylinder at a time by pulling the wires,and that didnt make the clack go away.I am figuring it is a collapsed piston skirt or a wrist pin{I build race car engines as a hobby and have heard a few noisy engines in my day},but I am surprised it hasnt gotten worse in 50,000 miles.I was wondering if the car might have done this since it was almost new.I plan on freshiening up the engine over this winter,but I would hate to go thru all this only to find out that these cars had some EGR valve malfunction or some kind of valve lifter problem that caused this and only end up with a noisy 'new' engine.So do any other 350 TPI owners have stories of the clack that didnt quit?Thanks in advance.

 

my car has a 89 305 with a serious thunk noise. so badly that you can feel it in the pedal when the car warms up. i replaced all the bearings in teh engine save teh cam bearings( none of the bearings was particularly bad). the clunk was gone for 30 mins and came back. i think its either the crank is outa round or sumthin in the cam. but the thunk is deep and you can feel it so i dunno

 

Clacking could be a lifter , rocker or even an injector about to sh*t .