| Engine Timing Chain Test [message #343463] |
Sat, 18 May 2019 20:42  |
Bruce Hart
Messages: 1501
Registered: October 2011
Location: La Grange, Wyoming
Karma:
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Senior Member |
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Published in the GMC International Newsletter Fall 2006
Timing chains seem to start causing performance problems around 100,000 miles.
The following procedure can be used to test whether the timing chain needs replacing.
1. Remove all spark plugs and distributor cap. Rotate the engine by turning
the nut on the crankshaft in the opposite direction of the spark timing scale
till you reach top dead center.
2. Have some one watch the distributor rotor while you rotate the engine. Watch
the timing scale as it moves up the scale. When your helper sees that the rotor
is beginning to move, stop turning the crankshaft and note the number of degrees
of crankshaft rotation.
3.These degrees are relative to timing chain lash (stretching). Lash over 4 degrees
starts to affect performance, over 8 degrees loss of performance is noticeable, and
over 12 degrees means timing chain assemble is near failure and should be replaced.
Failure to replace the timing chain can destroy an engine if the pistons ever strike
the valves.
Author of this article is not known.
Bruce Hart
1976 Palm Beach
1977 28' Kingsley
La Grange, Wyoming
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