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| Joined: | 05-01-2005 |
| Location: | Minneapolis, Minnesota USA |
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1 Tooth Pitch = 1 Tooth Width + 1 Gap Width...
or, from any point on one tooth to the exact same point on the next tooth.
You're off by less than a tooth width, not to mention gap width. Adjusting the pulley on the belt one full tooth pitch in either direction will only make matters worse. No adjustment you can make with non-adjustable pulleys will bring the timing marks into perfect alignment.
All that presumes that the crank is accurately set to TDC. if it's not, then 'SET IT TO TDC !!' and re-evaluate the cam timing.
Set the crank to #1 Cylinder at TDC by rotating the crank in a clockwise direction, and stopping cleanly at TDC without over-shooting or backing up. If necessary, instead of rotating the crank two full revolutions and back to TDC, it's acceptable to back-up counter-clockwise to ~30 BTDC, then reverse and rotate clockwise back to TDC... stopping WITHOUT over-shooting or backing-up and introducing any slack into the belt. Pull to a clean stop with #1 at TDC.
Anything that affects the distance between the crankshaft and camshaft centerlines will either introduce more slack out of the belt loop, or pull belt length back out of the loop. Things like dimension tolerances on all of the parts involved, a milled block deck or cylinder head, or a thicker or thinner head gasket (the modern composite head gasket's compressed thickness is 0.5mm ~ 0.020" thicker than that of the original steel-asbestos-steel head gasket).
Total tolerance/ error stack-up will cause a small mis-alignment between the two cam timing marks, but usually there is nothing you can do about it short of installing adjustable cam pulleys. Which raises the degree-of-difficulty bar considerably. For street driving, having the cam timing off by some fraction of a tooth width is not worth losing sleep over.
Regards,
Tim Engel
Attachment: 0 - 907 Cam Marks on JH.jpg (Downloaded 91 times)
Last edited on 03-10-2023 06:16 am by Esprit2