How to do power brakes.

[mmissile]

This may seem simple to most here, but I have cars with manual brakes and early engines.

I'm setting up 4-wheel/4-piston discs on a 67 Coronet/6.4 hemi. What master should I use?...Do I need an adjustable proportioning valve to the rear brakes?... and I'm hooking up a power brake system. Do I use a vacuum pump?

Thanks, Mike.

 

[BigYellaStella]

Master needs to have an 1"1/8" bore, an adjustable proportioning valve is ideal to dial it in to your own preferences, make sure to remove any residual pressure valves in the front lines (or just change them out entirely to new lines) and a vacuum pump is necessary only if the cam has alot of duration and overlap.

Generally, 112-114 degrees of lobe separation and a duration less than 270 degrees @. 050 lift are what you're shooting for to allow the engine to create adequate vacuum.

Vacuum pumps are nice if you NEED one & don't mind the noise they make(they all sound like an on board air compressor) but buy an extra vacuum switch if/when you buy it because they go out at the worst possible time.

DON'T buy a Vacuum reservoir thinking it'll take the place of a pump because they don't. The price point between them makes it a no brainer BUT in a stop and go cruising/traffic situation they deplete quickly and kill power assistance.

If your engine pulls 18-22 inches of vacuum at the manifold, then you don't need either the pump or the reservoir, if it's 12-18 then you can chance it with the reservoir, if it's less than that then a pump is the only way to go.

 

[BigYellaStella]

Remove any residual pressure valves in the rear line too, didnt read close enough saw you're doing a 4 wheel disc conversion.

Hope this helps!

 

[mmissile]

Don't see an obvious vacuum source on the 6.4 engine. There's plenty of good deals on aftermarket PB setups.....now for the vacuum source.

 

[Mike67]

I've noticed a lot of people are starting to run the hydroboost type boosters in classic cars instead of the big traditional vacuum boosters.
They ain't cheap....but I think there are many different mfgs with offerings..
https://www.google.com/aclk?sa=l&ai...=&ved=0ahUKEwjLkLyk04jPAhUGzmMKHQ79ApIQpysIVA

 

[69L48Z27]

I did a GM ProTour car and I used a setup similar to what Detriot Speed sells:

9" dual diaphram booster
1" bore MC, they use a GM version.
If using no booster you would use a 15/16" MC.
Adjustable Bear or Wilwood Proportion Value.

I ended up using all Wilwood 6 piston/4 piston calipers front/rear.

On the LS3 there is a port to pull vacuum off of, I would expect the 6.4 to have the same provisions somewhere, rear of manifold seems like the first place I would look. You don't say what the 6.4 is HP or cam wise but unless the thing is beating its guts out with cam you should be fine. Crate or stock take out should not require a pump or canister.

 

[mmissile]

I've noticed a lot of people are starting to run the hydroboost type boosters in classic cars instead of the big traditional vacuum boosters.
They ain't cheap....but I think there are many different mfgs with offerings..
https://www.google.com/aclk?sa=l&ai...=&ved=0ahUKEwjLkLyk04jPAhUGzmMKHQ79ApIQpysIVA

View attachment 360388

Not my car, and I'm not creating exyra work for myself. I've had more than enough time with the hydraboost install on my cuda project.