[U47]

Anyone know when Pontiac started using nylon/plastic coated aluminum cam sprockets? documentation would be great. I know I've replaced them on 64 330 Cutlass and 67 LeMans 326.

[Dick Boneske]

I don't know when the nylon use started, but my '64 GTO did have it on the top sprocket. The gear/chain failed at 55,000 miles. I think my '69 Executive Safari wagon with a 400 2 bbl. had the plastic on the gear, also. That chain failed at about 70,000 miles.

I can't remember whether my '73 and '76 Grand Safari 400's had the plastic-coated gear, but they both failed before 100,000 miles.

[mgarblik]

Funny story about those sprockets. The second Pontiac I ever owned was a 66 Ventura 389. The guy I bought it from lived 2 houses away. I bought the car for $300.00 from the original owner. Started it up backed out the driveway drove home and the cam sprocket shed it's teeth in the driveway and the engine stopped. My father came out the front door and said, Looks like you bought a real lemon there!. It was a yellow car with black interior. That was the only time that car ever let me down for the next 150,000 miles.

[Goatracer1]

When I worked for Pontiac back in the 1970's if a car came in with the plastic gear missing teeth we had to drop the oil pan to get those teeth because they tended to get in the oil supply holes in the crank. By the way, anyone want an NOS one? I still have one.

[ponyakr]

My '69 RA3 GTO had one. It didn't even make 50,000 miles.

Other than that, it ran great for 60,000+ street miles and 2 seasons of racing.

[Ben M.]

Originally Posted by Dick Boneske

I can't remember whether my '73 and '76 Grand Safari 400's had the plastic-coated gear, but they both failed before 100,000 miles.

I've taken apart a decent amount of low mileage 1972 & 1973 engines and none of them had the nylon coated teeth in them. My last one I even found the factory date code that was stamped on the gear (August 20th, 1973) on a car with 82k miles on it.

The GM promotional photos for the 1970 model year clearly show the nylon teeth on a gear, so it would seem sometime between 1971-1972 they stopped using them.

[mechanickeith]

Originally Posted by U47

Anyone know when Pontiac started using nylon/plastic coated aluminum cam sprockets? documentation would be great. I know I've replaced them on 64 330 Cutlass and 67 LeMans 326.

64 was the first year.

[U47]

Originally Posted by mechanickeith

64 was the first year.

Hi Keith, Thanks.
I have a Car Life magazine from 1964 which shows the new Gen2 Olds engine ( short deck 330 ) in pieces and includes this plastic coated cam sprocket. The article is very thorough on every aspect of the engine, but even though it mentions the nylon coated aluminum sprocket it does not say "new for this year" . I'm trying to solve this problem for a guy over at AACA with a 64 GP that has about 50K and never been opened up. My guess and with Dick Boneske's post below is that 64 is the year for it's introduction. Two years ago I rebuilt my 63 Catalina's 389 ( never been opened) and the sprocket was cast iron. I do know that Cadillac used nylon coated aluminum sprocket with the 425 engine 1977-1979 and the 368 engine 1980. Don't know what the HT4100 had. Also all the Ford FE 427 including the 425 hp. 2X4's engine had them.
The old story was they were designed to be quieter, but now I'm finding it has something to do with camshaft harmonic's.

[Mr Anonymous]

Dad bought a brand new Pontiac wagon in 1968. Didn't even make it home from the dealership when the cam gear failed!