John; I just took a look at my old chain and upper sprocket (which should
wear much more than the bottom one because of the much smaller number of
teeth),
and when I squeeze the chain around the sprocket I can barely lift the chain
up off the sprocket; I would estimate maybe 3 or 4 millimeters. When I try the
same thing with a new set I can lift it maybe a millimeter or two, so there's
a definite difference. When I look at the teeth on the old sprocket they
certainly aren't worn to a point - you can barely see the difference between
the
old and the new one - but nonetheless you can definitely see a difference in
the amount of looseness of the chain to the sprocket. Oddly enough there is
obvious wear on the back (cam) side of the teeth! When I take the old sprocket
with a new chain the amount of "lift" is a lot less than with the old chain,
but more than with a new sprocket. In my engine there was quite a bit of slop
and heavy wear to the upper guide (no contact with the "Evil L", though), I
guess caused by the idiot that machined down the bottom of the cam towers to
take up some of the warpage in the head. Maybe I didn't have to replace my
timing set, but it was easier to do it when everything else was being replaced.
I guess if I were you I would remove the valve cover and try to pull up on
the chain; if it doesn't lift up but a little bit, and if the teeth were still
flat on the point-end of the tooth I'd probably leave it alone. If the teeth
were worn to a sharp point I'd definitely replace everything. I've always been
told that if you try to put a new chain on old sprockets the chain will wear
very quickly until it settles in to match the uneven wear that you see on the
teeth.
My very uneducated opinion!
Fred Johnson
WI
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