I was curious my engine pulls about 12 to 13" of vacum at idle. When I rev the engine, to lets say adjust the carb, the vacuum rises up to the 18" they recommend. Is this setup normal conditions to run a power brake booster? Or do you need 18" at idle? I would think under normal driving conditions it produces the 18" needed vacuum.

I would say that your vacuum will be plenty good. People seem to complain about low vacuum affecting their power brakes, but I haven't had that problem on my 68. I have 5-7" of vacuum at idle. I use a check valve in the vacuum hose, and it sort of uses the brake booster as a vacuum resivior. (spelling!) The only issue I've noticed with my low idle vac, is the first time you use the brakes, if you haven't revved the engine at all after starting it, they are a little weak or hard to press. After the engine has spun up past 1000 rpm once, the vacuum is built up and the brakes work just fine. (my car is a stick with 4.66 rear gears if that would make any difference too)

chris