full manifold vacuum port
Racer
Joined: Feb 2013
Posts: 386
Likes: 3
From: Clifton Virginia
On mine, green arrow is ported vacuum since it was later style QJET. Earlier style I heard that port is full time manifold vacuum port.
There should also be another nipple on back of the carb next to brake booster vacuum port.
Thread Starter
Le Mans Master
Joined: Oct 2006
Posts: 8,941
Likes: 35
From: El Cajon California
If you have a QJET, look for nipples under the throttle plate on your carb like the one's with yellow arrows pointing to:
On mine, green arrow is ported vacuum since it was later style QJET. Earlier style I heard that port is full time manifold vacuum port.
There should also be another nipple on back of the carb next to brake booster vacuum port.
On mine, green arrow is ported vacuum since it was later style QJET. Earlier style I heard that port is full time manifold vacuum port.
There should also be another nipple on back of the carb next to brake booster vacuum port.
Waskelly Wrabbitt!!
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
How to you "set" air/fuel mixture with a vacuum gauge? You can adjust the idle mixture screws for maximum vacuum at idle [assuming that you have set ignition timing in an appropriate manner and made all proper adjustments to the carb and choke system and that idle speed has been set]. But that approach assumes that A/F mixture is optimized by achieving maximum vacuum at idle. Usually, a mechanic will make a final 1/8 turn or 1/4 turn of those mixture screws toward the rich side, just to be sure it will not be running too lean.
There are a number of methods which could be used to set idle mixture. Maximum vacuum is one of them.
There is a manifold vacuum port that comes out the right side of the carb via a tube that sticks out through the choke mechanism. Prior to emissions systems, this was the 'normal' fitting that connected directly to the distributor vacuum can. But, any "manifold" vacuum fitting will work; ported, or timed, vacuum ports will not serve for this purpose.
There are a number of methods which could be used to set idle mixture. Maximum vacuum is one of them.
There is a manifold vacuum port that comes out the right side of the carb via a tube that sticks out through the choke mechanism. Prior to emissions systems, this was the 'normal' fitting that connected directly to the distributor vacuum can. But, any "manifold" vacuum fitting will work; ported, or timed, vacuum ports will not serve for this purpose.
Last edited by 7T1vette; May 1, 2013 at 12:11 AM.
