master cylinder size

[trackster]

Planning on power brakes for the wife's '39 Chevy sedan.  GM metric calipers in the front and S10 drums in the rear.   Will a one 1" diameter master cylinder bore be sufficient or would a 1 1/8" or 7/8" be better?  Planning on a 7" single booster.  Thanks for any input you can offer.

[kb426]

I don't think a 7" booster will be enough for an 1.125 master. Any of the smaller choices would be better IMHO.

[enjenjo]

With the metric calipers used on an S10,and S10 wheel cylinders in the rear, the S10 master cylinder is 24mm and should be an ideal size. 24mm is .944"  The S10 master cylinder will fit a 7" aftermarket booster, but I would suggest a 7" dual diaphram booster. It does not take up much more room, and has a lot more boost.