Where was the Factory Vac Source for a B20 VAC

[Mark P.]

I have a 1967 small block 300 hp car with a powerglide that was a former K-19 car. The car has an incorrect distributor installed (1111087) and had a B12 VAC that I have replaced with a B20 VAC. The VAC is currently connected to a ported vaccum source on a Holley 3814 carb and I would appreciate if someone could explain the location where the factory connected the VAC to the manifold vacuum source.

Thanks--Mark

[Duke W.]

Re: Where was the Factory Vac Source for a B20 VAC

K-19 included the specific 3814 carburetor that was set up for ported vacuum advance, so there may not be a convenient full manifold vacuum source. If it has an external choke vacuum break, you can tee into that. There may also be a full time vacuum source for the Powerglide. I'm not familiar with the details of your specific configuration, so all I can offer is general guidance.

The other scheme is to tap into whatever provision is included for power brakes whether or not your car is so equipped.

Duke

[John H.]

Re: Where was the Factory Vac Source for a B20 VAC

Mark -

You can tee the VAC hose into the line that runs from the intake manifold vacuum fitting (behind the carb) to the Powerglide modulator, or tee it into the rubber hose from the front of the baseplate to the choke pull-off diaphragm, which sees full manifold vacuum. The 3814 carb doesn't have a manifold vacuum source.