I have a '88 IROC w/ a 350 TPI engine it and its been running great till this morning. It has over 150K miles on it and it is not raced or abused. This morning I started up my car, it was 33 degrees outside, engine starts with no problem, oil pressure was good, climbed to about 55 PSI. After about a minute or 2 sitting and letting it warm up I started hearing this chattering coming from what sounded the like th middle of the engine and from under the valve cover on the pass. side. I revved it up just a little and it would get worst as it revved up. It was not the water pump or power steering pump. I thought it might go away once it warmed up but it never did. Has anyone had this happen to them? I checked my oil just like 2 days ago and it was fine and I guess I should have checked it this morning but I needed to get to work. I have a 355 shortblock waiting to be built up so I figured if it blew up, just a better reason to get the 355 finished!

 

Give it a good long drive and see if it quiets down.

 

I talked to a friend in my car club, he said it is probably my timing chain. He asked does it sound like a set keys kinda clanging and scraping and yeah it does. He has '92 RS and has already had to put a new one on his so I am going to pick a double roller chain today and put it on this weekend. My timing cover needs to be re-sealed so might as well do it.

 

to remove the cover. You also need to have remove the harmonic balancer and crank shaft gear.

Also, very seldom does a T-chain all of a sudden start making noise. Its a long term gradual thing. Factory chains are normally coated on the top gear with nylon. They don't make noise even when they are worn out most the time.