I'm looking at doing the MP Brakes disk conversion. I was woundering if my stock booster will work with the disk master cylinder? I '66 Chevelle came stock with power assisted drum brakes and a 6 cylinder. I now have a big block and the booster clears the valve covers. Should I just pay the extra money and buy a new smaller booster?

Two things to consider there... first off, the drum booster will work with the disk MC IF the pushrod matches! Most of the drum boosters I've dealt with have used the long pushrod while most of the disk MC's have the shallow hole and require the short pushrod. This is not too big an issue as you can simply cut the long rod down to size. Just make sure they match!

Second, if you decide to go with the new, smaller booster, please make note of the vacuum requirements to operate properly! Most, if not all, of the smaller dual-diaphram boosters require MORE vacuum than the larger, single diaphram boosters!! I found that out the hard way and the smaller boosters can require up to 18" of vacuum to work fully!! And believe me, the smaller boosters are much harder to push when there is not sufficient vacuum!

Good luck,
Bill C.

Here's the answer right from MPBrakes' Site:

Q:I have power drum brakes, can I use the same booster if I change to disc brakes?

A:Yes. Just be sure to use a disc brake master cylinder.

Check out there site, they have a good tech reference area with a FAQ page and Set Up Page:
www.mpbrakes.com (http://www.mpbrakes.com)

Thanks