FWIW, I replaced a ruptured vacuum advance assy on my W & H DuCoil (not a DuPoint) and I had to place a physical stop in the vacuum chamber to prevent advance past 45 degrees at 2500 rpm... shimming only seemed to change the rate of advance. 

Should I have simply re-drilled a hole in the vacuum advance arm/plate attachment point?

Cheers... Brian

Cylinder Index = 84

Current Experiment = `57 Tbird, Grand Rapids, Michigan

Was it knocking with more than 45 degrees?


Lawrenceville, GA

I have had limited opportunity to drive it under heavy load but test driving it (some hard stomps, some gradual exertion, some crusing and coasting) around the neighborhood I have not yet notice knock/ping.

I thought I had read here on several posts that max advance should be 40-45 degrees... otherwise dont things start making unintended introductions at high rpm's?  Perhaps I mis-interpret what I read?

Cheers... Brian

Cylinder Index = 84

Current Experiment = `57 Tbird, Grand Rapids, Michigan

I forget, what year are you working with.



On a '57 and newer distributor, the additional advance provided by the vacuum advance can cause the total to be a good bit higher than 38 - 40 degrees. It allows the engine to be more efficient while cruising. If it's '57 or newer and not knocking, don't worry about it. Total advance should be determined with the vacuum advance line disconnected and plugged.



If it's a pre '57 load-o-matic, then I can't advise you on the matter.


Lawrenceville, GA