I was wondering if the plastic toothed timing chain gears were used in the TPI engines? I know my 83 and 84 Z28s had them, but I dont know if the TPI engines used them. My 83 was an LG4 and my 84 was an L69. Thanks for the help.

Jeremy

It's possible. The '89 L98 I rebuilt had pieces of nylon in the oil pan, presumably from when the OEM cam gear shredded. I also found a fairly new GM steel timing set when we pulled the front cover off.

my 88 iroc has steel timing gears and steel chain, stock

My 85 and 86 both had the nylon gear.

MY '86 HAD A NYLON COVERED GEAR. IT BIT IT AROUND 160,000 MILES. IT WAS A 5.0 TPI MOTOR. I JUST REPLACED IT WITH A DOUBLE ROLLER TIMING SET AND THE MOTOR IS STILL RUNNING GREAT.

My 87 had steel gears. Looks like this might be the cutoff year for factory steel.

I have worked on a bunch of 87s and I don't recall any of them having the nylon top timing gear. I'm sure that would have caught my attention if it had one.

88-up I'm almost certain they were all steel gears.

Hmm 87 might be the cut-off year. Thanks guys for all the info. We will see if this 88 Im getting ready to work on had nylon or not. Thanks again.

Jeremy

87 would make sense, since that's when the timing set changed for the factory roller cam.

That makes sense Aperion.

My TTA had a nylon coated gear, but they were flat tappet cammed as well.

My 91 Formula also had steel gears

later
Jeremy

At about 183,000 miles my 83 Z28 "died" on the way to work one morning. No gas, no spark, no oil pressure when cranking. When we tore the front down we found the chain had slipped off a very worn steel timing gear. It's an HO car/motor. I'm not saying it's the original gear, but it was pretty well worn down to nubs and it looked like a lot of wear for a replacement timing gear.