dont seem to have enough vacume from carb to booster only about 10 in running a 440 30 over 850 holly carb 7 in dual diaphram tuff stuff booster any suggestions?

more initial timing might up your idle vacuum a bit for when you let off the gas to brake. Might take the auxillary vac pump(electric?) to take care of them.

make sure the check valve on the booster works GREAT and doesnt leak down. pull it and do the old suction test (use your mouth and suck abnd blow- make sure it isnt leaky).

second, learn to drive differently. engine make lits of vacuum on cruise and deceleration. when you take your foot off the gas and let the engine brake, it makes A LOT of vacuum that the booster will store.

finally, get a vacuum resevoir and install it. i have 6-7" of vacuum at idle and brakes havent failed me yet.