[Cliff R]

"Ray Charles could see that the GM Nylon cam gear/chains were garbage. They affected all divisions back then, not just Pontiac. They were an engineering disaster. The take away is pure planned obsolescence."

In theory you get the best of the best with a nylon coated top sprocket and Morse chain set-up. They provide constant tooth contact, the strength of the Morse/link belt chain design, noise reduction, resist wear on the teeth, absorbs some harmonics and very smooth drive for the camshaft.

One of my mentors WAY back in the 1980's ran a very successful drag racing Class car and that's all he used on his engines. I even see him take the same set and move it from engine to engine. He said that it reduced "spark scatter", made more power and worth both ET and MPH compared to a roller style timing set.

Theory is fine and I'm sure the engineers meant well with those plastic coated top gear timing sets, however, like many other things that end up in and on these engines they were horrible in long term service. Thousand of heating/cooling cycles caused the plastic to get brittle and start cracking. Then the teeth would start to shred off the gear and end up in the bottom of the oil pan and oil pump pick-up screen. They would eventually fail without warning and leave you walking. It was a black eye for GM and they used them pretty much across the board until they had so many failures they went back to metal top gears again.

Tom has always said on here that "engineers do thing for a reason". I'm sure they meant well and saw benefits with the plastic top gear timing sets, however, as stated IF you look at that deal for a moment and think about one making it in long term service......pretty risky deal all the way around IMHO........Cliff