So I have a 70 hemicuda with stock hemi booster. It has been in storage for about a year and now has no power to the brakes. Car was restored in 2007 and brakes worked until now. I had the booster rebuilt during resto. Vacuum is about 16 mmhg at idle. Comp Cam 513 lift/292 duration @ 0" I think.
Doesn't give me any assist at any rpm. I can hook a vacuum from my Jeep to the cuda booster (22 mmhg) and get boost but it doesn't hold the charge at all when jeep is turned off. Tried a new valve, no difference. How long should it hold a vacuum? Would like some feedback before sending it out. help:

Well, it's supposed to hold vacuum long enough to make at least a couple of engine-off stops. If the check valve and its grommet are good the diaphragm must be leaking.

Can you hear any leakage immediately after the engine is shut off?

Not really, but kind of hard to hear with engine noise when it it leaks immediately. Don't hear any hiss. Any recommendations for rebuilders?

Booster Dewey seems to be a favorite.

http://www.boosterdeweyexchange.com/

The Ram Man might have some answers for you:

http://www.theramman.com/

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