Yes, the smaller Booster will "function." If you were to do a comparison you might notice a difference between the two with the nod going to the larger booster. Yes, you could use the Booster from your Drum Brakes.

Summit's Customer Service ethic is great, so I'd suggest that you call Summit and explain that you screwed up and see if they are willing do something towards getting you the larger Booster you really wanted.

 

That larger booster traps and stores a larger amount of vacuum. A smaller brake booster probably won't matter to an engine with a cam shaft that makes "normal" amounts of engine vacuum. For use with a more "radical" cam, that smaller booster might not store enough vacuum.

Rick

 

I have the 9 inch in my car and 244/248 cam. Works fine.

 

Disc brakes need more line pressure, so I think the 9" booster will not be enough. It works on diaphragm area. 11" booster has 48% more diaphragm area than a 9" booster, so the 11" will provide substantially more brake assist. Vacuum works on the diaphragm.

 

You'll have to ask her >

 

Is it a slim 9" booster or a regular 9" booster?

I have a slim one, and it sucks (no pun intended.)

As soon as the weather breaks and I can get back out there for test rides, I'll be doing something about my brakes, including replacing the slim 9" booster with something more useful.

 

Its a regular 9". I will probably use the original 11" from my drum brakes.

 

I have 8" dual diaphragm on my Cutlass and 9" on my Impala and they both work just fine with no noticeable difference from 11".