Thread: Engine cranks; no compression?
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Old Dec 27, 2015 | 11:44 AM
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onehundred80
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Default Re: Engine cranks; no compression?
Originally Posted by cdrance
The diagrams provided are correct, and are similar to the service manual. However, by design of a 4 stroke engine, the marks must align every other revolution!!! Drive gear has 180 teeth (20 degrees apart). Cam gear has 36 teeth. Cylinders fire every other revolution.
For anyone that needs to change the timing chain, this is what the manual says (supported by the drawings posted):

Typo in the above it would be 18 teeth on the crankshaft pulley.
You are correct though, firing is every 120 degrees. I baffled this old brain with maths.
I still doubt the engine has slipped a few links. I have had it happen on a Ford 302 engine and it slipped a tooth at a time more or less and the performance went down reasonably slowly, quick blips of the throttle made it jump a tooth or two.
The chain was like a limp noodle when held out on edge. Finally the pistons hit the inlet valves if I remember correctly, not a pretty sight.
 
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