Fixing A Vacuum Issue Is Easy With A CPP Electric Vacuum Pump

Hot rodding is a wonderful thing. There are a million parts out there that will help you make more horsepower, others that make your trans shift harder and faster, and others that have you stopping and handling like a modern muscle car. The problem is there’s often some kind of trade off. In the case of this 383-powered ’64 Chevelle, an improved induction system meant a decrease in vacuum to the power brake booster — not a good thing. Fixing this vacuum issue made for a safer, more enjoyable ride.

Hot rodding is great, but every change can affect something else. We used the electric vacuum pump kit from Classic Performance Products to give us back the vacuum lost when we switched to a low-rise crossram intake manifold and dual throttle bodies. (Photo by Ed Zinke)

Vacuum issues can come from other changes, too. Everyone likes the sound a long-duration camshaft makes. Younger enthusiasts call it “the chop,” old timers will let you know you have a three-quarter race cam (or even a full race cam). These bumpsticks sound great and, if chosen properly, will add copious amounts of horsepower, but they can also kill vacuum, leaving you in need of more.

These are the vacuum readings we got after the new intake was installed: Left is at idle, right is at 2,500 rpm. This is not enough for any power brake system, let alone a car with four-wheel discs. (Photos by Ed Zinke)

When this author installed four-wheel power disc brakes in his ‘65 Dodge, it was a huge improvement over stock drums with an unassisted single-pot master cylinder, but there was not enough vacuum to keep the booster working to its full capacity. Twenty-five years ago, the solution was a simple vacuum canister, which was OK, but it was definitely not consistent or optimal.

Zinke's tried and true power brake/master cylinder combo was in good working condition (left), but the switch to an Offenhauser low-profile dual-ram intake and dual throttle body setup from FiTech left him severely lacking in the vacuum department. (Photos by Ed Zinke)

A Better Vacuum Solution

In the case of this particular ’64 Chevelle with four-wheel disc brakes, owner Ed Zinke found a more elegant and far superior fix after he found his power brake system lacking. Ed had installed FitTech’s cross-ram dual throttle body fuel-injection system on his small-block. Ed found the cross-ram EFI setup to be the answer to his hot rodding dreams. He loved the way it started and ran, the instantaneous throttle response — not to mention the lack of fumes in his garage when he shut the car off — but the switch to the long-ram Offenhauser intake left his brake booster with a shortage of vacuum. What to do?

The CPP electric vacuum pump is fairly compact, so there was no problem finding a place to mount it. Ed used the driver's side inner fender. He held the pump to the fender, marked the spots to drill for the holes, then got out the trusty drill. (Photos by Ed Zinke)

To fix this vacuum issue, Ed turned to the Classic Performance Products (CPP) parts catalog and ordered an Electric Power Brake Vacuum Pump kit (P/N CPEVP-K).

This inexpensive part ($299) was all he needed to not only fix the vacuum issue, but give him more than he had with the old single four-barrel setup.

The CPP Electric Power Brake Vacuum Pump Kit is 100 percent complete and includes a pump, bracket, tee, check valves, hardware, and sensor. It’s a model of simplicity, meaning it is easy to install, and ensures reliable brake performance.

Drilling was easy (we recommend hitting the open holes with a little paint to keep rust away), then the pump just bolts in place. (Photos by Ed Zinke)

Now, there’s no problem whatsoever when it comes to hauling his ’64 Chevelle down from speed. The CPP electric power brake pump kit delivers all the vacuum the car needs and it does it consistently, from the minute Ed starts the car to when he shuts it off.

Ed used an Allen key on the vacuum switch to add two psi of vacuum to the pump (for a total of 20). Wiring is simple: The positive goes to a 12-volt with the key-on, negative can be grounded. (Photos by Ed Zinke)

Testing, Testing …

“I road tested the car and the product has eliminated the hard pedal with limited brake application due to lack of vacuum the the power booster,” Zinke told us. The pedal is now responsive to the applied foot pressure providing various stopping levels of braking for the booster.”

Here's the pump totally installed. One vacuum hose goes from the brake booster, under the master cylinder, and to the tee on the inner fender. The other large vacuum line comes from a port on the intake manifold (not shown) and runs behind the alternator into a check valve next the the engine ECU. With the engine running, vacuum was now 20 psi, more than enough for any power disc brake setup. Since this was photographed, it has been adjusted to 22 psi, which resulted in a more controllable pedal, according to the owner. (Photos by Ed Zinke)

Before the electric vacuum pump, pressure to the booster was a meager 11 psi at idle and 14.5 at 2,500 rpm —not nearly enough for a modern power brake system. After the install, vacuum was a steady 20 psi. After shutting the car and letting it sit for three hours, Ed hooked up the vacuum gauge and it reported 20 psi — no loss of pressure whatsoever.