[SFfiredog]

Sorry to hi-jack the thread but one more question for the expert(s). What is the basis for backfiring on only one side of the engine(passenger)? No timing changes, no exhaust leaks & using webers? You can email me your thoughts to keep out of this tread? Thanks! [/b][/quote]

Tony,
Seeing how the engine ran fine before it was dissassmenbled the backfiring is most likely being caused by the throttle linkage on the passenger side being slightly out of adjusment. This might have happened when you had the heads off.
Disconnect the linkage an make sure the throttle blades are all closed the same amount. The tiniest variance in blade opening can cause backfiring.
HTH,
Mike