classicgen
Member
I synchronized with the spark advance as instructed below and that took out a lot of the vibration I had, however, I still have a slight surging at lower and mid range rpms. I rebuilt the carb and that made no difference. I have new plugs in as well, new fuel pump, new lines, etc. It was surging prior to me rebuilding the carb so that made no difference. Any advice is appreciated.
"That sounds like the throttle roller cam is not synchronized with the spark advance, not a air/fuel leakage condition.
Notice the scribe mark on the cam that contacts the throttle roller. That mark should just touch the roller when it it dead center with the roller. This is the point where the throttle butterfly should just start to open, not before or after.
Now (engine not running), put engine in forward gear. Apply full throttle and make sure that the timer base under the flywheel is absolutely up against the full spark advance stop.
With the above set as it should be, adjust the brass (or steel) collar on the rod that leads from the vertical throttle shaft to the carburetor linkage so that the throttle butterfly is perfectly horizontal (full throttle).
Let us know if this cures the problem.
"That sounds like the throttle roller cam is not synchronized with the spark advance, not a air/fuel leakage condition.
Notice the scribe mark on the cam that contacts the throttle roller. That mark should just touch the roller when it it dead center with the roller. This is the point where the throttle butterfly should just start to open, not before or after.
Now (engine not running), put engine in forward gear. Apply full throttle and make sure that the timer base under the flywheel is absolutely up against the full spark advance stop.
With the above set as it should be, adjust the brass (or steel) collar on the rod that leads from the vertical throttle shaft to the carburetor linkage so that the throttle butterfly is perfectly horizontal (full throttle).
Let us know if this cures the problem.