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Discussion Topic:
Carburetor Idle Mixture Screws - No Effect?
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supereal |
04-23-2014 @ 2:42 PM
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Senior
Posts: 6819
Joined: Oct 2009
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At our shop, we have been turning the gasket surface on power valves to eliminate the radius. This seems to cure the leakage, particularly with the triangle gaskets.
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TomO |
04-23-2014 @ 7:25 AM
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Senior
Posts: 7264
Joined: Oct 2009
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As a rule of thumb, if 1 gasket does not seal, 2 gaskets will increase the chance of a leak by 100%.
Tom
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carcrazy |
04-22-2014 @ 5:18 PM
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Senior
Posts: 1682
Joined: Oct 2009
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Thank you gentlemen. Thanks to your excellent advice this problem has been solved and the idle mixture screws now have full range of authority. The power valve was the culprit - the sealing surface had a radius that prevented it from making a tight seal even with two gaskets.
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Old Henry |
04-21-2014 @ 7:10 PM
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Senior
Posts: 738
Joined: Apr 2010
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Also, make sure that the throttle plates are closing all the way. Screw the idle speed screw out far enough to make sure. Any air or gas leak anywhere will defeat the idle screws.
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supereal |
04-21-2014 @ 5:48 PM
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Senior
Posts: 6819
Joined: Oct 2009
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Pull the needles and inspect the tip to see if they were over tightened. If you see a ring, chances are the seats have been enlarged to the point the needles don't seat. Also look for a vacuum leak around the carb or intake manifold. A cracked or loose wiper hose will affect the idle circuit.
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ken ct. |
04-21-2014 @ 4:00 PM
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Senior
Posts: 1513
Joined: Jan 2010
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Engine is getting gas to run from a leaky power valve or a bad gasket there.Replace PV with a 5.5 and a proper gasket. ken ct. You will also need a base to middle section gasket.
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cliftford |
04-21-2014 @ 12:39 PM
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Senior
Posts: 845
Joined: Jan 2014
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My guess is the power valve, gasket, or the vacuum passage that controls it is at fault.
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carcrazy |
04-21-2014 @ 11:13 AM
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Senior
Posts: 1682
Joined: Oct 2009
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The carburetor idle mixture screws have no effect on the idle quality when turned all the way in. What is happening?
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