[fourjudge]

I have a fairly low mileage 1970 455 motor (66K miles) I am cleaning up. I have the timing chain cover off and the timing chain seems to have a fair amount of slack. Should there be any slack? If so, how how deflection is acceptable?...meaning, if one side is taught, how much should the other side deflect and still be OK? Mine "loose" side deflects about 1/4". Thanks for any help!

[fourjudge]

I have a fairly low mileage 1970 455 motor (66K miles) I am cleaning up. I have the timing chain cover off and the timing chain seems to have a fair amount of slack. Should there be any slack? If so, how how deflection is acceptable?...meaning, if one side is taught, how much should the other side deflect and still be OK? Mine "loose" side deflects about 1/4". Thanks for any help!

[Squidward]

I just replaced mine last night while replacing a badly corroded timing cover. I checked chain deflection, and it was a good inch or more (bbbaaaddd!!!) after being replaced during last engine rebuild 40,000 ago. The new chain deflected maybe 1/8" at most on the loose side, but there was essentially no deflection for all intents and purposes. This might explain why my car has been running progressively more & more sluggish over the last year.

You might as well replace it. I put a new stock-type chain on it for $24. I have a stock-type application (daily driver), so I didn't need any adjustable timing sets or anything fancy.

"...ridge reamer and ring compressor? Do they have tools like that?"

[61man]

If you've got all of that stuff off, just replace the chain and gears. You can do this for under $75.00 and then not worry about it for another 50-75000 miles......

http://kurtspontiac.homestead.com/Pre1964Pontiacs.html

[Robert Williams]

While you have the cam gear off i would remove the cam thrust plate and check it for excessive wear. Also check the groove and spurt hole in the plate and the groove in the block for blockage.

Robert Williams