The MGA With An Attitude
Timing Chain and SPROCKET WEAR -- CM-107

At 05:51 PM 11/24/2008 -0800, Kenneth James wrote:
"How does one determine if it is time to replace the time gear and or the timing chain?"

Lay a sprocket flat on a table then pick it up with one hand with fingers on the teeth. If it cuts your fingers with sharp ends on the teeth it's time to replace it. The crankshaft sprocket has half as many teeth and goes around twice as fast as the cam sprocket, so that crank sprocket will wear at least twice as fast.

Timing chain is a little more subjective. If the tensioner runs out of travel and leaves the chain slack it is certainly shot, but we hope they never get that bad. Hold the chain flat and stretch it out long and narrow, holding one end only. If it holds up fairly flat and horizontal it should be good to use. If it sags in a substantial arc it's shot.

Greatest wear point for a timing chain is in the link pins. as the pins wear they get more running clearance, and the chain gets longer when loaded in tension (and sags when held sideways).

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