My dad just bought a 57 Ford. Y-block, 239. Has the original carb...2 barrel. Its running rich and fouling out the plugs. This carb looks like a holley 2300...but there are no mixture screws on the side of the metering block like most holleys! How do you adjust this carb?...Im not near the car now for pics or numbers...can get that tomorrow after work...An ideas?
Well first off 57s did not have 239s that was 54 only, you have most likely a 272 being that it has a 2bbl. Look down low on the carb base front side for the screws.
there are (were) a few steps to a real tune up. page 1-8 here. http://www.forelpublishing.com/demo/jrwells/demo10157.pdf There are 32 procedures ahead of touching the idle mix screws. (Although I'd be tempted to at least try that first, noting where they are now)
The mixture screws only affect idle and even full rich couldn't foul plugs. That carb has a vacuum diaphragm power valve. When the diaphragm fails it will suck fuel straight into the manifold causing a gross rich condition. http://www.holley.com/data/Products/Technical/199R10013.pdf The reason they fail could be age or backfire, as listed in another thread you can get a backfire protector. jm2c rh
A properly jetted car running on the main or cruise circuit should be a touch lean. Put it up to about 2500 RPM and block the throttle to hold it at a fixed RPM. If you introduce a good sized vacuum leak it should miss a bit or lose some rpm. If you get a substantial increase in RPM the there is too much fuel available. If there is no increase or a miss you can use propane to see how lean you are. These cars ran on the rich side but I would expect to see 50 - 150 RPM bump a you slowly meter propane into the airhorn. Go slow and fine tune to get the maximum RPM.If you get a big jump in RPM, 200 -500 then the primary metering is too lean. Remember too rich can be cause by many factors, float level, flooding, internal carb leaks. In summary if adding air cuses a RPM gain, you have excess fuel, if adding fuel causes an increase you have excess air. This link is for checking vacuum leaks with propane but the general idea is the same. http://www.highperformancepontiac.c...to_identify_engine_vacuum_leaks/photo_12.html Use common sense, if you are unsure, just don't do this. This is how I would check the mixture control when the first electronic carbs hit in 78. Hoop CAUTION Propane is a flammable gas. Observe "no smoking/no open flame" precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.
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