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Henry has working power brakes now. They’re a little touchy, so I turned the proportioning valve down to minimum on the rear brakes to keep them from locking up so easily. I have front disc brakes planned, but I wanted to get the new master cylinder installed, new lines bent, and the power brakes working first.
To get enough vacuum for both the PCV valve and brake booster, I installed a 1” thick aluminum spacer under the carburetor and drilled and tapped it for a 1/8” NPT to 3/8” barbed hose fitting. The original vacuum passages for the windshield wipers were simply too restrictive. With the PCV connected through them, manifold vacuum would drop to around 2” Hg.
The spacer provides a direct manifold vacuum source for the PCV and brake booster, and while I was at it, I drilled it for a carb cheater setup as well. Started with 1/4” fittings, I figure that gives me some adjustment size up and down if needed.
Here’s a photo of the spacer.
Holes I plan on using for carb cheater. Left is a 3/8” barbed fitting, threads are 1/8” NPT.
I'm not sure to what extent having the ports biased to a barrel would have an effect. The larger truck manifolds have the larger line for the brake booster on the manifold. The ones on smaller trucks and passenger cars can be drilled and tapped. This one is blocked off with a hex headed plug:
This is where the 11/16 DOT heavy reinforced walled brake vacuum line would attach.
I saw that and thought about drilling and tapping that hole, I do have that flat spot. I didn’t want too have to take the intake manifold off. If I ever have the intake off I can take a look at drilling and tapping that spot.
The spacer gave me a bit of flexibility, the port I drilled for the brakes and PCV is down the center and gets vacuum from both cylinders. Also allowed me to drill a couple of ports for carb cheater. I need to get a few exhaust leaks fixed and install carb cheater to get the AFR meter and see where it’s at.
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Henry has Power Brakes
