Timing curve for my big-cam 451?

I believe there's a # on the vac can arm which relates to what vacuum will pull it in.I can't find the article I read . I'm not an expert but you may want to see what # you have and go with the lowest # available.Some thing you may not have considered. Also (I think you may have already done this) Turning to screw CW in the advance all the way in should make it react at 5 inches of vacuum.