Hello Got a brake booster incorporated into my hoped up 34 Ford. Due to the lumpy cam and blower I have not enough vacuum to keep the booster always charged. Coming down from higher revs with throttle closed the booster seems to work and generates extra brake power but when cruising I only get around 7 to 9 psi which seems to be lowish for the booster. Is there an electric vacuum pump that controls booster vacuum on its own - i.e. it pumps until max vac is reached and stops til vac is low again. All the modern pumps that I find here comunicate with the modern car electronics - which I don´t have in my 34 flathead. I think an electric pump will be damaged soon if it should run all day. Anyone done this? Thanks!
I installed this one on my friends El Camino with a big lumpy cam in it. It works well and only runs until the set vacuum level is reached. https://www.summitracing.com/parts/cvs-vp665
Do you really need power assist in your '34 braking? Would a pedal ratio or master cylinder size change help enough? If power assist is needed, a hydroboost conversion may be your best option.
I’m all for the pedal ratio for braking but it goes along a smaller diameter MC bore and proper diameter wheel cylinders if using drum brakes which many do on the rears.
well, first thing would be to put it at the carb, above the blower, where all the vacuum is. Might fix your problem for free.
A large brake vacuum resevoir may also help, https://evsource.com/cdn/shop/products/vacuum_resevoir_1024x1024.jpg?v=1507062724
Or, one could use an alternator that mounts a vacuum pump on its back. Used on a lot of small diesel trucks. I have one off a Mitsubishi that I saved for a future project. Probably never get to it, but I've got it! Downside, ugly on a clean looking engine.
Some update: I put the boosters hose on the carb to see if there is more vacuum available. Slightly better but not much difference in town so I got a vac pump that was driven from the alternator of a Diesel car. Will test and report back.
Hello from france I had the same issue on a 1956 olds 98 with an iskederian cam inside. I first tryed an electrical waccum pump, but no luck that didnt worked fine. I mounted a modern diesel waccum pump and all worked fine
Like @squirrel said above, the vacuum above the blower is the best source. My flathead has a 471 and big cam and I have 15-16 pounds up there continuous. I use it for my PVC system. On mine, I tapped the carb adapter. I actually tapped it twice (plug visible behind fitting) for tune up vacuum source.
Brake shoes seem to bed in now after a couple 100 miles, braking has improved since changing to vac at carb - thanks Squirrel! Maybe a booster tank could help a bit while in city traffic.
Meanwhile I have used the car a lot more. Almost every sunny day we were riding somewhere. Brakes have improved quite a bit but I still wanted to know if a booster tank would help even more. So I made a tank with around 1,5 ltrs. There was just enough space in the frame rails. It does help a lot in city traffic.
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