Are any of you team Chevelle ers familiar with this vacuum pump?
http://www.gmcmotorhome.com/tech/vacuum_pump/index.html
Can anybody tell me how many inches of vacuum this pump is capable of producing?

There's another post around here about this topic. I can tell you that I have on installed on my '69. It pulls a lot of vacuum...I believe it turns on when vacuum falls below 15 inches then shuts off again somewhere around 25. Don't quote me on that.

My big-block only pulls around 10 inches, so I thought the vacuum pump would be the way to go. Don't get me wrong; it does work. It's just that I'm not entirely pleased with it. I've found that on long down hills where I have to use the brakes a lot that I'm still getting a hard pedal at the bottom, with the pump racing to catch up. It works very well, but I'd just as not have to worry about those certain situations where the pump can't keep up. So I'm considering a hydraulic booster setup. It connects to the vehicle's power steering pump, assuming you have one. Wilbur can tell you more.

Thanks for the info on the vacuum pump Larry...
I know the vacuum hose goes to the brake booster. How bout the hose out of the pump(blow).Did you hook it up to the intake or just let it open.
Any info you could give me on this pump, and for plumbing this pump would be very helpful. I don't want to do the hydraulic booster at this time without trying the vacuum pump....
Thanks to all for help and info ~ ~ ~Randy

The other line runs to the intake manifold or carb base, where the brake booster vacuum hose would normally go. Basically, the pump is sitting inline with the stock setup. This way the engine vacuum will still pull through the pump and the pump is there to pickup the slack. Make sense? I've been using this setup for 2-3 years now. The pump doesn't always keep up, but does a decent job. I bought one brand new at the dealer (big $$), then realized they were plentiful in the junkyards and picked up 2 more for $15.

I have one and it pulls about 18" of Vacuum - I got 2 at the junkyard for $10 Each with the isolated mounting bracket.

Thanks guys...I knew you would pull thru with answers.
I picked one up at the local jyard, but it will only do 7". I liked the size and setup but the inches of vacuum they pull(even new) scares me.
Am considering an aftermarket pump(gast)introduced to me by team member Mikehartwell.
This pump is supposed to do 23". Any thoughts or comments? TTA~~~Randy

How much is the Gast? I got mine from MasterPower brakes. Fairly pricey it was.

Here is all that I have now on this pump.Just started to do research on it now that I have decided NOT to use the GM type pump.

http://www.camaros.net/forum/ultimatebb.php?ubb=get_topic;f=7;t=004994#000000