Hot Rods marginal power brake performance

has anyone used a vacuum reservoir or an electric vacuum pump to help power brakes when you have a big cam

 

General Motors comes to mind with the earlier tuned port injection. I had a couple of the pumps I bought at swap meets years ago and the worked pretty good on a small engine crankcase evacuation system…

 

I've been happy using an electric vacuum pump to make power brakes work. I suppose a mechanical pump would be ok but it means adding quite a bit more hardware.

 

The newer GM performance cars with blowers = Cad CTS V have a vacuum pump on them to provide vacuum to the booster. back in the 7.3 days Ford Diesel pickups had a belt driven vacuum pump for the booster. A number of cars had vacuum reservoiur cans back in the late 60's and early 70's though.

The aftermarket electric vacuum pumps aren't all that spendy do a search for Cadillac CTS V vacuum pump. One listing even will give you a listing of possible donors if you want to go scrouging pick a part.

 

do these pumps run all the time or do they cycle as needed to maintain the necessary vacuum

 

A Master Power vacuum pump I just installed only cycles enough to meet demands.

 

As needed, I believe mine kicks on at 16 iov and off at 22 iov

 

Not psi…. Inches of vacuum.

 

As noted above, a vacuum switch cycles the pump on and off as needed.

 

A reservoir alone won't increase performance, rather it just adds several more cycles of the pedal at engine vacuum.

A pump alone will increase performance.

A pump and reservoir is better.

A pump, reservoir and biggest booster you can fit is best.

My 7" dual was marginal, even with can and pump on a 3600 lb car and 20" vacuum.

Going to a 9 in dual with pump and vacuum can made the brakes amazing. I also ditched the cheesy switch in the kit and used an adjustable trans vacuum switch for best reliability.

 

Hydroboost.

Hydraulic brake booster, that runs off of the power steering pump.