Anyone ever replace a large (11") booster with a smaller one, like a 9" ?? Not sure what the difference would be for braking. And some boosters are listed as have one or two diaphrams (?) I need a smaller booster, to get some clearance on the rocker cover of the Caddy engine in the Elco.

It maybe hard to tell in this pic but I have a smaller booster and tall valevcovers for roller rockers. It works fine so far, the vac assist seems to be the same. Sorry it aint such a pretty pic.
http://s1031.photobucket.com/albums/y379/centex396/?action=view&current=002.jpg

im running the smaller one in mine needed clearance for master for clutch can't say that i notice any difference.:smileyb:

The smaller ones are usually a little longer front to back, because they are a double diaphragm unit. They offer just as much (if not more) braking assistance as the large diameter units. They also allow more room for bigger things in the engine bay.

Note the size of the booster: http://i110.photobucket.com/albums/n114/kern-o/BigBlockfit003.jpg

Thanks for the quick replies! The ones I see listed show both single and double diaphragm types. So a double type would work right? The extra length shouldn't be a problem.

And thanks for the pics centex and Kerno !