Thanks Dick.
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Dave---It should not matter where the slop is that causes the timing
variation. The shop that rebuilt your motor should stand behind their
work. If you want to investiga this yourself, you can try the follwing:
By working backwards, one should be able to see at what junction the
play is at. For instance:
Take off the dist. cap and hold onto rotor by hand. (By putting the
transmission in top gear and slightly rocking the car, it will) Move the
crankshaft forward and back to see how many degrees it moves before you
feel the rotor try to turn. Or...
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[Dave] This was what I did (with the engine builder) to determine the ~10
degrees of play. Using a timing light set to catch the farthest retarded
illumination of the timing mark and then the farthest advanced illumination
of the timing mark and determining the difference also showed ~10 degrees of
variation.
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Take out the distributor and watch the drive gear motion as you move the
crankshaft forward and back. If there's stil lost motion, this removes
any worn distrbutor bearings from the picture. Or...
Remove the dist. drive gear and watch the gear on the cam, as you rotate
the crank forward and back. (Tricky, but do-able)
One of the above steps should uncover the reason for the timing
variation, as 10 deg. is far too much. On my engine, if I reverse the
direction of the crankshaft, the rotor will change direction within two
deg. of crank change.
The stock chain tensioner is capable of removing slack, when installed
(correctly).
Dick
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