Gentlmen: I am so close to being on the road I can taste it, But I have one small problem. I am getting so much manifold vacuum that the power brakes stay on,I have to lift the pedal to release the brakes. Yes this makes for a great solution for emergency brakes but I would like to go down the road not sit there. I would take any suggestions at this point (Keep it nice now) I am running a 350/350 combination, Edlebrock performer intake and Carb.
Any engine will only make about 21-22" of vacuum max (at idle and choke open) so your problem has to be elsewhere. You will get a larger volume as engine size increases but this isn't a problem, in fact, the vacuum wipers on a 51 GMC with a 500 Cadillac engine we did years ago still work perfect--even uphill. It takes good cylinders, rings, valve stems/guides, and a bone stock cam along with proper tuning to get this figure. To verify this get a cheap vacuum guage from Auto Zone or other FLAP store to check it out. You might shorten the rod from the pedal into the cylinder or even hook a really strong return spring from the pedal arm to an under dash bracket. Anything you use your foot on can have a very strong spring and not be a problem, just think of the clutch linkage return spring--that sucker is strong. Your problem is in rod length or the linkage, not vacuum. Good luck;
Vacuum Brake Dragging What Evan said ~ 1st. you must ensure the brake pedal hits the backside of the toe board with a ' thunk ' every time you release it . Then , check the clevis pin to ensure it has freeplay (rattles) when the brake pedal is released . No such thing as ' too much ' engine vacuum ! .
