Can anyone help confirm what master cylinder should have come on my 1967 Olds Cutlass? Restoring the car and threw the old 4 Bolt Master Cylinder (Chrysler style) away assuming finding another would be easy. Every part source only shows the typical 2 bolt mounting style units. It was an a drum car and had a 4 bolt square mounting flange like the attached. 4 studs emerging from my firewall. Now, my was a dedicated race car for years, perhaps this was added for race reasons, not sure. But nobody shows this style for my 67 Olds. Is now front disk, rear drum. Should I use the Chrysler master cylinder?

 

I believe you may be seeing 4 bolts or 4 bolt holes for a power brake booster. All 67's used the 2 bolt master cylinder for manual or drum brakes.

 

Oldsmaniac,
Its murky for me as I see many underhood pics of these A-bodies without power booster. Im sure power brakes was only an option. So, this car had the 4 fastener (like Chryslers) square flange on it as it was mounted to the firewall. Seems to me a 2 bolt mounting would only be appropriate mounting on a booster. There are other pics online of these mid 60s A bodies with the same 4 bolt square flange that was on mine. Its all very murky to me...

 

The 4 bolts on the firewall are only used if the car had a power brake booster. If car was originally manual brakes only 2 of the 4 were used. Master cylinders look the same but too are different between power brakes and manual brakes.

 

Here is a picture of my 67 non power brake car. 4 studs are there only 2 are used for the master

 

I assume your car is manual disc brakes? If so, that's not OEM, so there is no telling what the previous owner who installed the disc brakes did. The correct M/C for a 1967 disc brake car looks like this, but note that manual disc brakes were not offered in the 1967 model year, only power disc brakes. You can use an aftermarket manual brake M/C, but be aware that the GM-style M/C has the FRONT reservoir feeding the front brakes. That Chrysler M/C has the REAR reservoir feeding the front brakes. You'll need to swap the hard lines at the M/C to use the correct one. Again, you'll first need to really understand what was done to this car to ensure you don't make a "destructive improvement".

 

All of you guys are so right...I get it now. I hadnt realized the top 2 bolts (with centered hole) accepts the standard 2 hole master cylinder perfectly. I hadnt realized that. Oldsmaniac, yes, your pic of the firewall is exactly like mine....4 studs, but the hole centered btw top 2 studs. I got it now! Many thanks! And here is my old girl. Chris.

 

That four bolt M/C actually had the pushrod misaligned since the bore is not in line with the top two holes.

 

Yea Joe, you are so right. That 4 bolt Mopar master cylinder had a central bore, wouldnt have lined up at all. Many thanks to all of you. I got it now!