Adding a vacuum port to an "A" manifold

Adding a vacuum port to an "A" manifold

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By paul2748 - 15 Years Ago

I need to add a vacuum port to my A manifold to run some accessories. Does any one know if there is enough thickness to drill and tap a hole in the rear of the manifold about where the "B" manifold has a vacuum source. If not, is somewhere else better?

Thanks

By pegleg - 15 Years Ago

Paul,

If it were I, I'd find an aluminum spacer to go under the carb and drill and tap that. The manifold wall will only be 3/16 or so thick..........if you're lucky.

By rick55 - 15 Years Ago

I'd go with Frank's suggestion also. If you were to drill the manifold and botch the job the manifold would be toast.

Put a 1/2" - 1" spacer on the manifold making sure you drill through to between the front or rear carb ports.

I don't know about the availability of spacers for teapot carbys though. Plenty out there for the later carbys.

If you already have the manifold adapted for the later Holley you should have no problem.

The 1850 Holley already has the vacuum take off point integral with the carb base plate.

Regards

By John Mummert - 15 Years Ago

I have an A manifold here that has a boss cast in front of the carb for a vacuum port but it was never drilled. Cast at an angle to catch both runners.

By rick55 - 15 Years Ago

Hi John

I have two A manifolds - one with the boss cast in and one without.

The one without the boss, someone in the past drilled a hole and tapped it but it is only into one runner. I was told that it came off a 55 Thunderbird = but then doesn't everything.

The one with a boss is a clean skin - untouched- and came off a 56 292 ECZ motor..

It is interesting that Ford recognized the need but didn't drill it.

regards

Rick

By paul2748 - 15 Years Ago

The reason that the 56 wasn't drilled is because ford rerouted the vacuum lines to the back of the carb. The 55's had them drilled. I guess when they went to the 56 configuration, they used the same casting but didn't drill the holes.