Originally posted by manny
I would try retarding the ignition timing a few degrees, before I would look at shims.
If the C/R is actually higher than before, you could also try the very highest octane gasoline that you can find.
I'm running 98 Octane petrol. Have been for the last 8 months.
There's also some chain slack that the new chain tennsioner didn't take up, which can't really be solved by any other means.