Distributor Advance Instead of Retard?

[Targalid]

I cleaned my 1976 911S distributor and reset the total advance per Gunter's distributor maintenance thread. I have the Bosch distributor with vacuum retard of 5 degrees at idle. Total advance is set at 33 degrees at 6K rpm. The 5 degree retard was required by California pollution regulations at the time. Later distributors have a 5 degree advance at idle. Under load, I should have 33 degrees advance. When cruising, with less throttle, I should have 28 degrees total advance because of the vacuum retard fixture, correct? Distributors with the 5 degree advance fixture should have 33 degrees advance under load but cruise at 33 plus 5 or 38 degrees total advance. This is better for both performance and engine temperatures isn't it? So, my question: can the retard mechanism, held by two screws to the side of the distributor, which rotates the timing plate, be replaced by one that advances the timing 5 degrees? Or, do I look for a complete distributor that has vacuum advance instead of vacuum retard?

[Bob Kontak]

Vacuum retard is taken from intake vacuum. Once the throttle is opened, the vacuum in the intake drops and the function of the vacuum retard goes away.

It is meaningless as to total advance.

[Bob Kontak]

Originally Posted by Targalid

Distributors with the 5 degree advance fixture should have 33 degrees advance under load but cruise at 33 plus 5 or 38 degrees total advance.

No

You cruise at 2800 RPM. You are not maxed out on mechanical timing.

You are thinking this too hard. 33 is the max timing you should have - ever - and that is at high RPM's. There is no plus five or minus five. The retard goes away fast and the vacuum advance plays out prior to 6000 RPM and the mechanical takes over.