Loose timing chain diagnosis----1962

emmd61

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Hi. I have a decent 62 crown coupe. When I go to start it there is a rattling sound and engine timing seems off. Once running I do not hear a rattle and timing seems to be off still. I was concerned about stretch on timing chain. Before I go through the effort to remove/replace it I was hoping members could give advice on diagnosing timing chain stretch. Thanks again!!
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With engine off, set timing mark to zero, remove distributor cap and rotate crankshaft counter clockwise until distributor starts to move. Note movement of crankshaft. If it is more than 10 degrees you have a stretched chain or bad camshaft gear.
 
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You would also want to rotate the crank back and forth several times to repeat the results, this way you are taking up the slack in one direction and measuring it in the other direction. Have a helper place a socket on the balancer attachment nut for this test and be sure the key is in the off position. Another quick check is to take a timing light and note the amount that the mark appears to jump back and forth from TDC with the engine running, do this with the vacuum advance disconnected. This method is not as accurate as rotating the crank but it does give an indication of how much slack is in the chain and gear set. You can check your timing while you are at it using this approach.

Dave
 
Default . . . if the engine has over 80K miles on it, just replace it with a quality steel cam sproket and new chain. Normal type is fine, but for best long-term use, a quality roller timing chain set is just a bit more money. Either way, "cheap insurance" against future engine issues from a "jumped time" motor.

Check the see where the base timing is AND also what the point dwell is. If the timing is a good bit "off" and the dwell is still in spec, that might be easier to do?

Just some thoughts,
CBODY67
 
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