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By Joe-JDC - 6 Years Ago
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Have you ever had a carb that just would not idle properly? Nothing you do will make it work properly, new kit, cleaned, supposedly professionally rebuilt? I had the good fortune to buy an intake with carbs some time ago, and the seller said he could not get it to idle, or run properly. Did everything to try to get it run on his vehicle, and finally put it up for sale. I figured I could fix just about anything to do with the carbs, so I completed the deal. When I got the intake and carbs in the shop, I took everything apart, and gave it a good once over. There was half a dirt dauber nest in one side of the port deep in the manifold. It was still wet from all the fuel that had tried to wash it away! Next, it was cleaned up, flowed on the SF-600 flow bench, and then ported. Fast forward, and installed on an engine, and, you guessed it, it would not idle properly, and one idle screw had no affect on idle quality no matter what was done. Pulled the carbs off, took the carb apart, and removed the idle jet screws and springs. Uh-Oh! One brass screw had the whole tip buggered up, and missing the point. I shined a light down the passage, and the tip was broken off and lodged in the base of the carburetor so tight that I had to get a 90* scribe and knock the tip out backwards of the passage. Someone had screwed the idle mixture screw in so tightly that it literally welded the tip of the screw to the aluminum housing of the carb base, and when trying to adjust the screw out for idle, it broke in to. No air could flow through that passage. I installed a new idle screw with a sharp tip, and now it should idle like a newly rebuilt carb should have all along. Will check it out Monday to see if that was the whole issue with idle quality.
Here are a couple of pictures of the problem.
The tip was completely broken off and stuck so tight, I was afraid the seat would be ruined, but seems to be OK. All it took to find the problem was simply removing the idle screws to check for foreign objects in the passages. A simple brass screw tip broken off, and a sold intake with carburetors because the problem could not be solved easily. Joe-JDC
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By NoShortcuts - 6 Years Ago
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Life is a test, Joe. Congratulations on solving this one! 
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By FORD DEARBORN - 6 Years Ago
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Greetings everyone: Excellent detective work Joe, I love it. This is one of the many things, I believe, that draws us to this cool engine. We are challenged to put on our thinking cap in order to achieve a goal or solve a problem. We can't simply open up any one of the numerous speed catalog or hot rod magazines and buy what ever we can afford, bolt it on and go.
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By Ted - 6 Years Ago
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Good detective work Joe. That explains why one screw was responsive and the other was not during the dyno session.
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By Talkwrench - 6 Years Ago
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Takes a person with special needs to do that one  ... Well done for finding it!
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