It isn't either/or. The vac Advance is added to the mechanical advance. It does add to total timing which is why you have to unplug it to do ANY timing. When your done timing the engine, you plug it back in and it adds to what you have. It also completely goes away under load. All (non computer controlled) engines with Vac Advance also have Mechanical Advance. Not visa versa.
45 degrees is too much total timing, but not too much total plus vac advance. But don't time your engine this way. Disconnect the vac advance to time your engine.
Bob
Quote:
Originally posted by SCOBRAC
Seriously though.. John. 45 degrees is way too much how did you measure that an advance light or ? at some point 2800-3200 rpm you should see it stop. Regardless whether you use a mechanical or vacuum advance it should top out at 33-38 degrees..
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