I ordered a Right Stuff disc brake conversion kit (front only) for my Vista Cruiser. I got it today and it has a 9 inch booster, I was expecting an 11 inch. My fault, I didn't double check it when I ordered it. Will it matter with a totally stock 330 engine? I would think it would make enough vacuum. Any opinions?

 

Single or double diaphragm 9"?

 

Single as far as I know. Another option is to just use the 11" booster that is on the car with the drum brakes.

 

I'd go with the 11", but check the actuator of the booster to master cylinder to make sure they are compatible.

 

Get the right stuff on the phone
buy a few more things

No mix drum / disc old / repro parts brake system

 

A single 9" will give you a third less power assist versus the 11".

You will definitely notice that difference.

 

Note that the 64-66 cars came with a 9" booster from the factory. GM went to the stronger 11" booster when disc brakes became available in 1967.