sorting out a disc swap

[slant67]

A few years ago...for my '67 Barracuda, I'd gotten all the factory a-body specific Moparts I thought I'd need from the Spring Fling Swap to convert my small bolt pattern front drums to power discs...
And a couple of years ago...while I was away for a few months for work...a High School Auto Shop Teacher friend of mine who's since moved away went ahead and did the swap for me...
He said that he thought it needed more vacuum to work correctly and I thanked him for his generosity..
And then, the car sat for a year or more, as a shelf in the garage. Very sad.
I'm finally getting around to sorting out the brakes...
I've driven it around a bit...and for a brief moment, it does feel like I have power brakes...then, just a stiff pedal.
My vacuum is coming from a port on my Holley 4bbl, and though I haven't gauged it, a basic check by both me, and the guy at the local brake shop...implies that I'm getting enough vacuum.
I had even put in a vacuum storage canister to see if that would help...and it didn't do much good, just as a tester. I pulled it out.
The brake guy thinks that I need a new booster...or to rebuild...
My concerns are:
A) Is the brake valve type specific to power vs. manual, or disc vs. drum that I'm overlooking, that could be causing this whole thing?
B) Might it be just a faulty booster?

Thanks for any help you can offer!

 

[slant67]

this site is a wealth of assistance and creative genius...
I've found that the proportioning valve is different from drum to disc...
and that this might be the root of my problem.,
so, in theory...this might be easier than I thought.
Any corroboration would be greatly appreciated,
Thanks, again!

 

[goldduster318]

I have a drum brake distribution block + an adjustable valve on my car with the front disk brakes and it's working fine.

You could have a faulty booster. Do you know if the port on your holley is full time vacuum or just ported vacuum? Ported vacuum won't be active at idle. They typically hooked these directly to the intake manifold.

Do you know if your 1-way check valve is working properly?

 

[67Dart273]

The original brake distribution block is not really a valve, it's a switch and distribution block. It's purpose is to switch on the warning lamp if front - to - rear pressure gets to be very much different, indicating a leak at one end.

I still maintain "the easy way" is to add an aftermarket, adjustable prop valve to what you have.

If you have an "all drum" cylinder, you either need to change to a disk/ drum cylinder, or else remove or destroy the residual valve in the master (rear) which feeds the front disk brakes.

There's been many guys who maintain that one of these cars with disk/ drum brakes does not NEED boosted brakes

I myself am a little different.........I'm running 73/4 disks on the front, Linc Versaille on rear, and using the factory NON boosted 67 cylinder (not sure of bore) I just punctured the residual valves in the cylinder.

Now, I'm an old guy and my legs are not the best anymore, and I have no trouble locking this thing up

 

[1969383S]

Below the throttle valves is full vacuum. If the engine is in good operating condition it should be fine. Like said the frame block is just a distibution valve and safety switch. What bore size is the master cylinder?

 

[slant67]

thanks, all!
I do believe that the port on the carb gives constant vacuum, and that my check valve on the booster is functioning correctly...
And though I have no idea what bore my master cylinder is...I'll check.
I'm going to go ahead and rebuild nearly everything...but also get a new proportioning valve first.
Thanks again!