How to Block the Vacuum Fitting on a Holley Carburetor

The Holley carburetor has three vacuum fittings. The large port on the rear of the carburetor under the float bowl supplies vacuum to operate the power brakes. A small vacuum port in the base plate in the front of the carburetor features a constant vacuum used for the vacuum advance in the distributor. The last vacuum port is located on the passenger side front of the carburetor on the valve body between the body and the float bowl. This vacuum is a ported vacuum that supplies vacuum above idle. It is commonly used for the transmission modulator.

Instructions

1

Determine which vacuum port needs to be blocked, keeping in mind the purpose of each port. If there is no use for a particular port, then blocking it will maintain the vacuum needed within the main body.

2

Locate the proper vacuum blocker out of the kit that fits tightly on the port and push it on.

3

Block the port of choice using the proper diameter piece of hose and bolt or screw to seal it, if you do not have the proper vacuum blocker.