67 427 3x2 Intake Manifold Full Time Vacuum Source

[Thomas N.]

Hi:
Underneath the nipple for the PCV valve on a 67 427 3x2 intake manifold is a small freeze/expansion plug. If this plug was removed, would this be considered a source of full time vacuum? Picture is enclosed highlighting the region of interest on the manifold. Thanks for any responses.

Vacuum.jpg

[Duke W.]

Re: 67 427 3x2 Intake Manifold Full Time Vacuum Source

I assume you are talking about a L-71 and there are easier ways to convert the OE ported vacuum advance to full time. First is to get a 1/8" tee and a couple of feet of 1/8" vacuum tubing. Remove the existing choke vacuum break vacuum hose and make a new harness from the existing vacuum source to the choke vacuum break and VAC. This is an easy an inexpensive, totally reversible modification that can't really be detected with the air cleaner installed.

A second way it to remove the center carburetor and modify the vacuum passage to place it below the throttle plate. It involves plugging one passage with soft lead shot and drilling another passage. It's pretty easy to figure out what to do once you inspect the vacuum passages in the base plate, and it's invisible.

You also need a new VAC. The OE 15" 201 15 does not pass the Two-Inch Rule, so it needs to be replaced by a 12" B26.

Duke

[Thomas N.]

Re: 67 427 3x2 Intake Manifold Full Time Vacuum Source

Duke:
Thanks for your information. Is this region where I'm pointing on an L71 intake full time vacuum? The plug is already removed on this intake.

[Joe L.]

Re: 67 427 3x2 Intake Manifold Full Time Vacuum Source

Duke:
Thanks for your information. Is this region where I'm pointing on an L71 intake full time vacuum? The plug is already removed on this intake.

Thomas------

Yes, that fitting should provide full-time manifold vacuum.

[Thomas N.]

Re: 67 427 3x2 Intake Manifold Full Time Vacuum Source

Joe:
Thanks for the response!