Hi,
Just for clarification, on the original TR6 cam sprocket (aka chainwheel),
there are two sets of holes. If you draw a line bisecting the two holes of
each pair, you should see that one pair bisects the "peak" of the teeth,
and the other _should_ bisect the valley. So, you can get +- "half a
tooth" of adjustment.
For some strange reason, I cannot recall the number of teeth on cam
chainwheel, but I think it's 42. That said, a half tooth equates to about
3 degrees of adjustment.
The TR6 chainwheel cannot be flipped over *front to back" for two reasons.
One - the "dish" on the front face does not indent the same amount as the
"cut" on the backside... if you flipped the gear around front to back,
you'd likely need a _lot_ of shims to keep the crank sprocket in line with
the cam sprocket. The second problem is that the TR6 cam chainwheel is
drilled for oiling. Without the oiling holes, the timing chain would only
get "splash" from the crank snout - this would likely be inadequate.
There was a point some years ago where the pacific-rim supplied
chainwheels were not drilled correctly. I had one of these and the two
sets of holes were exactly symmetrical with the peaks of the chainwheel.
After that episode, I wound up spending $150 or so to get a cam vernier
setup... that allows infinite adjustment of the cam so you can play with
cam advance to make your power curve move around. I have not purchased a
new chainwheel for quite some time (maybe 7 years), so this quality issue
may have been addressed since I had direct experience. Caveat emptor! And
_measure, measure, measure_.
Hint - as much as 5 degress of cam advance will yield more power in a
stock TR6. But only your dyno can tell you if it works for you!
rml
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