Big Cam No Vacuum

One clever way to get better vacuum at idle is to use Rhoads leak-down hydraulic lifters. They give less lift at low rpm and full lift by 3000 rpm. The "variable valve" of newish sporty cars (aka Hondas) is the same idea. Gives better mileage and low-end torque as well. But, you lose that lopey glug-glug sound that many adore as the mark of a "race engine", plus the noxious fumes that do with it. The sound is from combustion gases blowing out the exhaust unused. But, unknowing people adore the noise and smell.

Diesels generate no intake vacuum (wide-open throttle on most), but still use vacuum accessories, especially brake boosters. Newer ones use small electric vacuum pumps, one dedicated to the booster and often another for door locks. You can buy used ones cheap on ebay, look for VW, Audi, etc. (~$30). I bought one to rig for my M-B diesels for when the very expensive mechanical vacuum pumps fail. You would also need to buy an adjustable vacuum switch (~$30). Or you can pay >$300 for an aftermarket one in race magazines.