nm9stheham
Well-Known Member
For those of you with older /6's, here is an example what happens to the timing chain as it wears. The first pix is of the old one and you can see all the slack hanging below. The 2nd pix is of the new replacement chain set and the slack is minimal.
The chain slack/wear can be judge by turning the crank pulley back and forth by hand and seeing how far it moves against the timing tab with just modest effort. (The crank will turn but the cam will not if you don't turn too hard.) This old chain allowed the crank to loosely turn 6 degrees. The new chain allows it to turn only 1 degree. That eliminates 5 crank degrees of slack.
This difference in old versus new chain slack is a measure of how many crank degrees by which the cam is retarded with the old chain versus how it came originally from the factory. 4-5 degrees is a significant change in engine operation. Test drives after this chain replacement showed very notable improvements in:
- Idle stability.. no more 'hunting' in the idle speed
- 'Off the line' torque and perkiness (typical with advancing cam timing)
- Smaller throttle openings for the same acceleration and cruise
- Better throttle response at highway speeds
So if you can turn your crank easily back and forth by 3-4 degrees, you ought to be considering a new chain. More slack than that, and you should definitely do so. A new stock style Cloyes chain does not cost much (and there are better chains out there), and the installation is easy for a modestly experienced mechanic.
The chain slack/wear can be judge by turning the crank pulley back and forth by hand and seeing how far it moves against the timing tab with just modest effort. (The crank will turn but the cam will not if you don't turn too hard.) This old chain allowed the crank to loosely turn 6 degrees. The new chain allows it to turn only 1 degree. That eliminates 5 crank degrees of slack.
This difference in old versus new chain slack is a measure of how many crank degrees by which the cam is retarded with the old chain versus how it came originally from the factory. 4-5 degrees is a significant change in engine operation. Test drives after this chain replacement showed very notable improvements in:
- Idle stability.. no more 'hunting' in the idle speed
- 'Off the line' torque and perkiness (typical with advancing cam timing)
- Smaller throttle openings for the same acceleration and cruise
- Better throttle response at highway speeds
So if you can turn your crank easily back and forth by 3-4 degrees, you ought to be considering a new chain. More slack than that, and you should definitely do so. A new stock style Cloyes chain does not cost much (and there are better chains out there), and the installation is easy for a modestly experienced mechanic.