what size cylinder should I use after a 73-76 disc/10" drum manual brake conversion (70 Valiant w/all 9" drums)?

Since no one else has chimed in, I would start out with stock size cylinders for the rear 10" drums on a 73-76 disc brake car. I'd also consider going with an adjustable proportioning valve instead of the stock combo valve from the disc car.

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63 Valiant Wagon
225 - 4 bbl

I'd go with stock cylinders from same said year of car.

The prop block is a point of contention as 2 different combo valves were used in those years, one is just hollow and drilled for the appropriate valving sized and most common in 1973-1975 cars....1976 (and certain later F-bodies) drum cars got that valve, and the disc brake cars got one that is much like those seen on the disc brake E-bodies, these seem to work better than the former version (probably because the 1973-1974 OEM caliper bores were slightly smaller, and the rear cylinders were of a different bore).

-D.Idiot

Thanks for all the replies.

Since posting this I found that I'd have to change my rear do do 73+ brakes.

(I didn't want to change rims or rear.)

I got stuck buying new front drums (old one warped).

I may as well get my money's worth out of that setup for now.

Should I return to this line of thinking (i.e. 73+) I don't know what the stock size is. (Rockauto lists like 4 different bores for every applicable year of every a body)

15/16" is correct for the LBP 10" rear drum brake rear cylinders.

-D.Idiot

And I think 13/16 is used if you have a rear brake locking first problem with the 15/16

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Yep, those were used with the 73-74 smaller front caliper bores...expect a little harder pedal to get it to stop.

-D.Idiot