70 Nova disc conversion questions

[70Nova4dr]

I have a 70 Nova four door and i converted the front to disc using Scarebird brackets. It uses 78 Monte Carlo rotors and Celebrity calipers. Just curious if anyone has any ideas on what master cylinder and prop valve i should use. I bought a disc/drum master for a 68 Nova and i was wondering if i can use a disc/drum prop valve. Anyone have any ideas? On a side note does anyone know if wilwood's 140-2285 kit would clear a 14x6 steel wheel ? I am running 14x6 steelies with dog dish centercaps . Thanks. Brandon

[MarkM66]

You could just ditch that prop valve and run an adjustible one.

[Apogee]

IIRC, the Scarebird kits use a 1990 Celebrity front caliper with a 2.5" [63.5mm] piston diameter. The factory disc kit for the 1970 Nova's had a 2-15/16" [74.6mm] caliper piston diamter.

If you're running manual brakes, I would suggest you use a 15/16" bore MC like those used on the 1976-1977 Malibu for a disc/drum application. Since you didn't specify power or manual, the disc/drum MC from the '68 Nova that you purchased could be either a 1-1/8" bore (power) or 1" bore (manual). The 1" would work, but might be more effort than you prefer. The coefficient of friction of your pad selection will have an effect on pedal effort as well. The larger 1-1/8" bore unit will not generate adequate pressure for your setup and will require excessive effort to slow the car at all, let alone rapidly.

Tobin
KORE3

[70Nova4dr]

It will be manual brakes , what about the prop valve?

[70Nova4dr]

I went to Advance Auto parts and ordered a master cylinder for a 76 Malibu with manual brakes (15/16 bore) It was a whopping $19

[Apogee]

It will be manual brakes , what about the prop valve?

For what you're doing, the factory disc/drum prop valve should be fine. As Mark suggested, an adjustable would be a better choice if you had to buy one IMHO just due to the added flexibility in the futre if you were to upgrade the brakes later on.

Tobin
KORE3

[70Nova4dr]

Thanks for the help, now i have to find a disc/drum prop valve. Mine was a drum/drum car...how stupid is that ?

[Tito]

If you don't already have the disc/drum prop valve (sounds like you don't) then I'd definitely recommend picking up and adjustable one (like THIS) and plumbing it into the brake line that goes from the distribution block (under the master cylinder) to the rear axle.

Like Tobin (and Mark) mention, an adjustable prop valve will let you "tune" the front/rear brake balance and get the most out of your brake setup. Also, if decide to step up to rear discs or change the front discs to something larger, then you can re-use the same prop valve and just dial it in again...

[70Nova4dr]

Whats gonna work best? I have a Wilwood adjustable prop valve sitting around. Wont a factory disc/drum prop valve provide enough pressure?

[70Nova4dr]

Which pedal rod am i gonna want to use? the master cylinder came with 1 when i picked it . Thanks

[pitts64]

Once you experience an adjustable proportion valve, you'll never want the stock unit...