I just recently installed a new master cylinder and brake booster on my 70 Malibu. The old booster was, I believe, the factory 11 inch unit and the new one I put in was a 7 inch unit. Everything bolted up real good, as the place I bought it from supplied me with a set of brackets that allows the booster to bolt to the firewall. The car will slow real nice now, with just a little pedal pressure but If I want to bring the car to a complete stop, I have to apply a ton of pressure to the pedal. I did bench bleed the m/c and my neighbor and I bled the brakes by going around the car 2 complete times. Any idea why I need so much pedal pressure to stop the car? Thanks for any help.

Not enough Vacuum???? How big a cam are you running? I had to run a vacuum canister to have good brakes.

Sounds like my problem too, I'm awaiting a new master cylinder to make sure its right

my cam is a Comp 268-H, surely thats not too much cam for a system set up to work with big blocks....

My cam is stock. 350 ci - 300 hp motor.

How does the vacumn canister work?

the engine sucks air out of this "canister" and the no air in canister sucks air out of the power brake booster.

How can a guy get ahold of the vacuum canister system and how is it mounted? Is it a big job to install? Thanks.

7 inch booster is probably too small. I switched from an 11 in. to a 9 in. and had the same problem. No amount of vacuum is going to overcome the problem if the booster doesn't have enough capacity. Go back to the 11 in. or try an 8 in. dual diaphragm. If you are keeping the small block, there is no reason not to run the 11 in.

Thanks for the info. I am thinking about a Hydroboost system also.

Originally posted by MikeD70Malibu:
How can a guy get ahold of the vacuum canister system and how is it mounted? Is it a big job to install? Thanks. mount it anywhere you want, i have it on the inner fender
it is easy, reroute the hose so instead of going into the power brake, it goes to the canister, and at the outlet of the canister, hook that to the powerbrake

look at jegs for their vacuum canister