Timing chain and FE

[JanGeo]

Assuming that the distributor is driven by the far end of the cam shaft if you see some ignition timing wondering around that sometimes indicates play in the timing chain - but chances are you are electronically timed off the flywheel sensor. A simple check would be to look in the oil filling hole at the cam lifter push rod motion while turning the engine crank back and forth to see if there is any delay in the valve motion which would indicate slop in the chain. As for the tensioners they are usually on the unloaded side of the pulleys so that wear would cause valve delay when they stretch. As long as the engine oil was properly changed when needed then wear should be minimal and consistant with other engine wear.

[smay665949]

In the high performance race world they are adjusting cam timing all the time. Typically a street driven Chevy 350 is adjusted to 0 degrees, 4 degrees advance and 4 degrees retard. Some performance cams come with 4 degrees ground into the cam.

Typically a stock engine is set to 0 degrees.

4 degrees advance in cam will open the valves slightly sooner which moves your power/torque band to a lower RPM because air starts filling the cylinder sooner.

Retard the cam 4 degrees and you will lose low-end torque and gain high-end power. This is because at higher RPM there is faster airflow so the cylinder has a chance to get more air pushed in.

Many new cars come with variable cam sprockets that make these adjustments automatically based on RPM or inputs from the computer.

A stretched timing belt will cause the cam to retard slightly which will move the power to the higher RPM because the length of the belt between the cam and crank pulley are a little further apart. Your timing is probably not anywhere near 4 degrees, if it is you are probably going to end up losing a belt.

[8307c4]

Chains don't get replaced at certain mileage intervals, only belts do.

And unless your car runs an interference engine there is actually little chance of any damage to the engine and I usually let belts go until they break (which is, granted, annoying when it does), but some cars do run interference engines and unless you're sure then you're better off replacing the belt every 80k.

But no, not chains, those we run until it starts to ticking.
Sounds a bit like low oil, not to be confused.