Checking for Vac leaks
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Tuned
Joined: Oct 2016
Posts: 255
Likes: 2
From: South dakota
Checking for Vac leaks
I have a 1973 f 250 with a 390 2100 series 2bble Motorcraft carb. I was checking for vac leaks today and found out I have leaks around the throttle shaft. Spray carb cleaner around the mounting gasket its fine but when i spray around the throttle shaft it changes engine speed. Is that normal and how much is allowed?
Cargo Master
Joined: Nov 2011
Posts: 3,354
Likes: 48
From: Great American SouthWest
I have a 1973 f 250 with a 390 2100 series 2bble Motorcraft carb. I was checking for vac leaks today and found out I have leaks around the throttle shaft. Spray carb cleaner around the mounting gasket its fine but when i spray around the throttle shaft it changes engine speed. Is that normal and how much is allowed?
Then you replace it
Fleet Mechanic
Joined: Sep 2014
Posts: 1,626
Likes: 78
From: NE Texas
Improvise
Rebushing or replacing are preferred, but sometimes cash flow limits what we can do. A quick 'field expedient' fix: smear oil on the shaft - only on the shaft - where it comes out of the carb. Clean the carb surface around the shaft with alcohol or acetone to make sure it is contaminant free, then apply a small bead of gasket sealant to the joint between the carb body and the shaft. The oil will keep the sealer from sticking to the shaft and but you will significantly reduce the amount of air getting sucked in. Not a permanent fix, but it will reduce the air leakage and may make the difference between the truck running poorly and running acceptably, and will buy you some time to save up for the more expensive repair. T
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