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Old 06-07-2022, 07:09 PM   #5
jayoldschool
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Join Date: Dec 2012
Location: ON, Canada
Posts: 2,151
Re: How to adjust the idle vent valve (B carb)?

B, manual choke. I must have known how to set it when I rebuilt it... but that was a few carbs ago. I'll check that link and BRB.

Ok, yes, I'd read that one already. No idle vent info in there. At this point, I will just go with "make sure it's open at idle and closed with any throttle application".

But I'm open to suggestions/experience!

Best info I can find:

Quote:
Idle Vent Valve:

Most carburetors today will use a movable atmospheric idle vent valve in place of the fixed external vent system. This movable valve will be held in an open position only during idle and park positions by carburetor linkage contacting the idle vent arm. Any tendency for fuel vapors to collect inside the float bowl will be vented to atmos*phere through this opening at idle and park positions. As car speed increases and throttle linkage is progressively opened, the actuating lever from the linkage will no longer contact the idle vent arm thereby allowing the idle vent valve to close. This action will now return the carburetor to the internal vent system thereby once again maintaining the same pressure on top of the fuel as entering the carburetor through the air cleaner.

It is important that the idle vent valve be closed during all periods of operation except at idle, otherwise excessive richness can be caused by the higher atmospheric pressure acting upon the fuel in the float bowl.
SOURCE

Last edited by jayoldschool; 06-07-2022 at 07:16 PM.
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