Dick, Vance;
Success, I have been able to remove 6-7 degrees of the ~10 degrees of timing
jitter. The largest culprit was the drive dog to drive gear play. When
assembled on the bench the drive dog fit tightly into the drive gear with no
play, when assembled in the car the drive dog did not seat as far into the
drive gear resulting in slop due to the tapered edge of the drive dog teeth.
Further play was eliminated between the rotor and the shaft (about 2 degrees
due to this slop). The dizzy set up consists of a two piece shaft (a shaft
extender attached to the end of the stock shaft) with a new top mounting
plate to hold the magnetic pick-up. The custom made extension had slop in
the rotor mounting. A small bead with the welder and some filing and all
the slop was removed from the entire shaft setup. There is some marginal
side-to-side play at the end of the new longer shaft that will get removed
in the next couple of weeks. I will have a machine shop create a new single
piece shaft (if possible, the tach drive may be a problem), re-bush the
dizzy housing and insert a bearing in the top plate to stabilize the shaft
as much as possible. Hopefully this will eliminate any remaining jitter.
The car is much more drivable at low speed/low rpm condition with the
reduction from ~10 degrees to 3 or 4 degrees of timing scatter. Thanks to
all your suggestions for things to check. Going back and redoing many of
the tests as a sanity check along with an evening thinking about how the
tensioner would/could impact the timing stability lead to the source of much
of my problem.
Thanks again.
Dave
Phone: 403-279-1979
Cell: 403-608-6354
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