My new bbc has around 10 lbs at idle will this be enough for my power brakes? I plan on using a slightly smaller booster as the big covers won't clear the stock one. Someone here said they are using a corvette style one that is smaller and it seems ok but i need some confirmation please. Thanks for your time, Ralph.

You mean inches not pounds.
in., not lbs.

You may need an additional vacuum storage can.

I did an MP Brakes conversion on my Elky awhile ago, and all over their instructions they stated at least 18 inches minimum http://www.mpbrakes.com/mpfaqboost.htm
See #7 on the FAQ list.

BTW - a LOT of good info here.

I have a 454 in my 65 with power drums and it only carries 7-8" of vacuum ideling in gear. The brake peddle will get hard if you do alot of parking lot or stop and go type driving. Normal on the road driving it works fine. The small booster may hurt the reserve capacity some but I'd try it.

Jeff
65 Chevelle

I converted over to a dual diaphragm booster myself and my experience is that 10" of vacuum will provide functional boost. Drop that to 7" and brake boost becomes iffy. Go still lower and forget about boost completely.

Note that on the bottom end the vacuum can fall off in a hurry if your idle speed drops much or at all. I have to always be ready for a non-boosted brake pedal whenever I am doing slow speed manuevers.

I have 10 or 11 (it bounces) on my BBC, and Power Brakes, no problem.

Fred.

Ok guys this makes me feel better as an electric pump is $350!!!! What size boosters are you using and single/double dia.? Ralph

I think mine is a 7" or 8" dual... it came off of a '79 El Camino at the Pick-n-pull.

Did it go in with no mods or did you have to do some work to get it in.

Some work was required... I ground the rivets off the old booster so I could remove and reuse the mounting brackets. I elongated the mounting bracket holes a bit for fit. And I cut off the end of the booster pushrod, threaded it, and added a section of threaded rod/bolt to get it to the same length as the original with the same clevis attachment as the original.

After that it was a bolt in deal. :-)

Hydro boost anyone?

Hydro boost anyone?
I would really like to... that would be the ultimate setup. Unfortunately it was hard to beat the cost of the dual diaphram booster. Not to mention the install simplicity.

I even went so far as to pick up an electro-hydro boost MC. Decided not to go there as the vacuum booster was still simpler. Gonna have to sell that MC one of these days.

I have hydro boost on my daily driver and am a believer.

I dont have power steering so hydro is out.

I dont have power steering so hydro is out.
Unless you go the electro-hydraulic setup... there are some mixed opinions of these units. But it is technically possible to have hydro boost even without power steering.

You can get a $10 electric vacuum pump from the junkyard out of an early 80's (81, 82, 83) Cimmaron, Citation or Pontiac J2000 Olds Omega. I bought 2 on my last scavenge trip and they both work great. Get the rubber mounted mounting bracket wth them.

See the atatched link -

http://www.gmcmotorhome.com/tech/vacuum_pump/index.html