Carl,
It does depend on the advance curve of your existing distributor, how worn
the springs are, and whether the vacuum advance unit is working properly.
However, I certainly do not subscribe to the theory that one should
arbitrarily disconnect the vac. unit just because there's a mild street cam
fitted!
The best way of setting the timing on an engine that has been modified from
stock is as follows: set the initial advance at whatever position gives you
36 degrees total advance at 3,000 r.p.m with the vac unit connected. Drive
the car and see how it performs. Repeat the test, again setting the initial
advance so that you get 36 degrees total at 3,000 r.p.m but this time with
the vacuum unit disconnected. Road test again. Decide which way was the
better of the two and either leave the unit disconnected or re-connect it
and re-set the initial advance setting. After that, each time you use the
car, adjust the timing a few clicks one way or the other, until you find the
position that gives you the overall best performance and fuel economy.
Lawrie
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