Hi I am lookig at this car for around $3800..105k..had timing belt/water pump done 55k. taking it to chevy dealer in Tampa Wed to look at before purchase..Seeking wisdom..What do I emphasize to mechanic for this car? the brakes/rotors new 10k..ac needs 1.5 to 2 cans last two summers owner says. CAr driven as number two car 3-4k per year.. Seems to start fine accelerate smooth..other than driver window not going down(owner says switch) and driver mirror not moving ( again switch) cant find anything obvious have receipts for brakes/rotors all at chevy dealer. Just want to know if there is any inherent flaws with this model. Should belt or chain be changed every 50k. Like I said 105k. what to look for.. Thanks all. Proff firefighter rookie sports car owner,,been a p/u guy for 20 years. Any reputable places in Tampa or FT Lauderdale to have work done on this Z28. again thanks a bunch

 

Welcome. Opti is a common problem for these bad boys.

 

For starters it's not an IROC, that was from back in the 1980's.
The engine has a timing chain, not belt. The chain lasts a good long time, doesn't break like a belt does, and doesn't need to be changed on a regular basis. With 105k miles, it should still be OK.
Any good mechanic should know what to look for on these cars, so emphasize to him to look "everything" over.

 

Not to argue that, but I have seen a chain stretch. But that was on a GM grumman with a 350 from the early 80s.

 

Yes that's true, chains do stretch as they wear. But I said chains don't break like a belt does, and they certainly don't wear nearly as fast as a belt does.
A lot of belt driven engines are interference engines, meaning when a belt goes, some valves get whacked by a piston. That's why preventative maintenance on those is important. A chain break is a more rare occurrence. When a chain gets real sloppy, a lot of times you can hear it smacking the timing chain cover, or you experience an erratic timing bounce that a timing light would show.

 

whats an opti for my gratification...owner said dealer replaced chain when he bought from dealer. seems weird a dealer would replace chain at 50k. well i am going to have mechanic replace switch in drivers door for window an look for leaks in seals listen for chain slapping and whatever.

 

The optispark is the LT1's exclusive distributor. It is mounted on the front of the engine, is driven off the front of the cam, is buried below the water pump, and is a pita to get to. The dealer changing the timing chain at 50k miles makes no sense at all, even if they were right there replacing the opti.