Replacement booster and master cylinder kit

[70chev]

Hey Guys,

My brake booster isn't holding vacuum like it once did. Any suggestions on a good replacement booster and master cylinder kit? I figure I might as well just change the master cylinder while it's getting done. My car is a 70 if that makes any difference.

 

Thanks! 

[jft69z]

I have a brand new booster with the delco morraine stamp, as well as a brand new NAPA master cylinder if you need it. The booster is the 'Right Stuff' one available everywhere. The master probably has about 50 miles on it, because shortly after I got the car on the road, I converted to 4 wheel disc.

The booster is new in box, because the Right Stuff sent another one as a warranty replacement because it seemed like I had a hard brake pedal. In the mean time, I got an original GM booster from a place in California, before the replacement one ever arrived. Exact same pedal feel, brake pressures front & rear the same, etc, which tells me the original Right Stuff booster was good too. NAPA warrantied the first master, just to cover all bases, and same pedal/brake pressures as well. Seems the engine vacuum is just low enough to cause the hard pedal. 

[Blackhawk]

Is the booster itself leaking or is the check valve shot?

[70chev]

13 hours ago, Blackhawk said:

Is the booster itself leaking or is the check valve shot?

Well, it is not holding vacuum, also has brake fluid running down it from the back of the master cylinder. 

 

My dad looked at it and said the vacuum line is not hooked up right either, which may have destroyed the booster. 

 

I have a line running off the back of the carb going to a "T" from the "T", one line goes to the booster, the other line goes to the PCV valve. 

 

So yea I have a mess 🤣😬

[cny first gen 71]

Sounds like you have a couple things going on there, first if theres fluid running down booster its probably leaking from back of master cylinder. Replace with a NEW one not rebuilt.  Check the check valve it is a one way valve and check the vacuum lines too for leaks. The way to check the booster is with the car not running pump up the brakes a few times the pedal should get hard,this depletes the vacuum in booster. then with your foot still on pedal start the car the pedal should fade down some if it does then the booster is probably ok. I have seen a few boosters go bad over the years and check valves too and of course vacuum lines. 

[70chev]

Is this a bad setup for the brake booster?

[Dtret]

Yes both should have individual vacuum source 

[cny first gen 71]

Can't get to my car right now but I believe it should direct manifold vacuum to the booster. PCV goes to back of carb.

[Dtret]

2 hours ago, cny first gen 71 said:

Can't get to my car right now but I believe it should direct manifold vacuum to the booster. PCV goes to back of carb.

I was going to say that but I wasn’t 100 percent sure so I skirted around it but I know what he has isn’t correct 

[Dtret]

The port hole for the booster is in front of the distributor (plugged?) but with the HEI it may be partially blocked. You’ll have to use a 90 degree port 

[70chev]

OK I will have to investigate my intake. Thank you!