car - basic V6 standard 65 special , drum non power brakes , "single" master cylinder . question - can i use a "dual" master cylinder from non power 67 chevelle ? i think that's the first year for the dual mc . if not what's the difference ?
You should be able to. Back in the 70s I pulled the power disc fronts, master cylinder, booster and proportioning valve off a 1970 Cutlass and put on my '64 Special that had the single master and drums. It was perfect fit and operation. And having a dual for safety is a smart thing. Make sure you have things set up so the front/rear is correctly isolated and "fail over/fail safe" functions as it should. (The rear of the master needs to have the same depth for the pushrod to the piston)
actually on car now . bought a new MC , all new lines and brake parts including wheel cyl's . added a manual adjustment rear proportioning valve ( skinny's up front , 275-60-15's on rear ) . gravity bleed all cyl's then worked my way around with my vac/bleed tool . pedal just not coming up , although it did feel a LITTLE better last time . maybe . working on interior and building shifter box for the 4 speed so it's not like it's holding me up - just perplexing . not like i've never bleed brakes before .
Answer: Yes. The main difference between a power brake master cylinder and a manual brake master cylinder is the bore of the piston, power 1 1/8", non-power 1". The conversion is simple: remove the rear line from the 4 way connector on the frame and plug the hole. Get a piece of brake line with ends that screw into the master cylinder on one end and onto the front-to-rear brake line on the other. Bleed the brakes and you're done. You only need a proportioning valve if you do a disk brake conversion.
