A QUICK QUESTION ABOUT MANIFOLD VACUUM

Mattax said
Not really. With a some extra overlap its usually least stable at idle rpm. But 3" Hg not sure I'd worry about it unless something else is going on.

Now why the advance isn't coming in before 1700 -rpm that would have me asking questions.

I double checked my numbers........That distributor actually comes in at 1500 RPM and puts 14* in by 2000 RPM. There must be a slight variation in tachometers. At any rate, the erratic needle occurs in the fast idle zone (with choke open obviously).