Nylon cam gear years

[legopnuematic]

My 79 (350 small block) had the original timing set blow up at some point, guessing late 80s as it was parked in 1993 and the heads had been redone and were very clean, and a new timing set installed.

The old chain was flopping around pretty good and wearing into the cover

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And found all this down in the pickup, parts of the gear, the garter spring for the front seal.

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[Turbo4whl]

I’m pretty sure all the classic GM engines are interference engines.

The 402 I spoke of had 8 bent valves, memory is bad but I think they were the intake valves. You could not see it until they were in the valve resurfacing machine.

 

[Toad455]

To each, their own. I am not a fan of timing belts either as I see that as a planned obsolescence. Timing chains are typically a life of the engine item if the engine is maintained and the gear & chain are metal in my experience. Most of the nylon coated ones I saw failed around 70K.

The nylon fell apart on my 69 Delta 88 with 455 engine and jumped time at 56K miles. It was the original gear set.

 

[AuroraGirl]

I believe the primary reason for the nylon teeth was a production issue. Was easier and cheaper to make the nylon teeth vs. machining the metal gear.

People love to hate on them, but they did usually last just as long as the rest of the car.

Noise and harshness is lowered

Misfires, knock, neglected oil, and early early nylon formulation lead to failures, but so would other parts in the engine for the same issues (first three)

The nylon gear turned out to be a VERY bad idea for the buick v6 and they used it through the 3.8l LG3 in fwd cars.
Its not uncommon to grenade the engine because of interreference valve contact because of failure at 80k or sometimes less. Sadly a lot of those old 1980s fwd car owners were burned by this , up to now. I see a person every few months come in the buick forums with the problem.

Timing gear on the ford 300 i6 being nylon makes them much quieter , but that doesnt use a chain.

 

[AuroraGirl]

Modern oil and lessons of the past help things

 

[ASPEC]

Well, parts are on hand and I will tear it down this weekend. I will post picks of what I find in there.