Editing How to rebuild automotive carburetors
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==Introduction== | ==Introduction== | ||
Sooner or later, every hotrodder runs into the steps of making induction and carburetion choices while building a performance engine. | Sooner or later, every hotrodder runs into the steps of making induction and carburetion choices while building a performance engine. | ||
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− | [[File:Oring holley sec.jpg|thumb | + | [[File:Oring holley sec.jpg|thumb|350px|Arrow indicates cork O-ring that seals the vacuum chamber to the main carb body]] |
Use a fresh cork O-ring to seal the secondary vacuum chamber assembly to the carb body. Using a light smear of Hylomar on the cork gasket helps it to seal and stay pliable. A small rubber O-ring may be used instead of the cork gasket to seal a Holley secondary chamber. If you try this, be sure the O-ring is sealing, w/o being ''too'' thick. | Use a fresh cork O-ring to seal the secondary vacuum chamber assembly to the carb body. Using a light smear of Hylomar on the cork gasket helps it to seal and stay pliable. A small rubber O-ring may be used instead of the cork gasket to seal a Holley secondary chamber. If you try this, be sure the O-ring is sealing, w/o being ''too'' thick. | ||
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− | + | Be sure the vacuum chamber is assembled correctly. The diaphragm can get misplaced/torn; if that happens there will be no secondaries. Also, the check ball can get left out or can stick or the check ball seat can be rough, allowing the secondaries to activate too easily. So be sure the check ball is present and the seat is well formed. | |
− | Be sure the vacuum chamber is assembled correctly. The diaphragm can | + | |
+ | The seat can be re formed by using an old check ball and a small punch. Drop the check ball into the check ball passage, then with the vacuum chamber solidly supported, lightly tap the old check ball with the punch and a small hammer. This re forms the seat. | ||
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'''NOTE:''' There are small grooves in the vacuum chamber check ball seat. This is normal, so do not try to use this method to remove the grooves. They need to be there to allow the secondaries to work correctly. | '''NOTE:''' There are small grooves in the vacuum chamber check ball seat. This is normal, so do not try to use this method to remove the grooves. They need to be there to allow the secondaries to work correctly. | ||
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The difference between the correct and too rich/lean jet sizes may only be 0.002”-0.004”. There are no readily available drill bits that are that close in size to one another. So at best, the changes made to jets by hand drilling are going to be in steps decided by the availability of drill bits. Because drill bits are often available in 1/64” increments (the small numbered bits- which have a finer increment between bits- are too small for drilling the average carb metering jet), this will be on the order of a 0.0156” change between drill bits- which is HUGE (~40%) change in metering area when in the 0.070” jet orifice range. | The difference between the correct and too rich/lean jet sizes may only be 0.002”-0.004”. There are no readily available drill bits that are that close in size to one another. So at best, the changes made to jets by hand drilling are going to be in steps decided by the availability of drill bits. Because drill bits are often available in 1/64” increments (the small numbered bits- which have a finer increment between bits- are too small for drilling the average carb metering jet), this will be on the order of a 0.0156” change between drill bits- which is HUGE (~40%) change in metering area when in the 0.070” jet orifice range. | ||
− | + | It is for these reasons there is no practical way for a person to casually drill a jet and have any way of knowing what the flow is going to be. Drilling out jets is a holdover from the dark days when guys were struggling to make “high performance” engines live, and if they got within 10% of ‘right’ they were at the top of the heap. Nowadays, thankfully, we all (should) know better and leave the drilling of jets and other dubious practices to the desperate, the uneducated, and the poverty-stricken. | |
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===Quadrajet Tuning and Repair Parts=== | ===Quadrajet Tuning and Repair Parts=== | ||
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==Carter carb== | ==Carter carb== | ||
− | + | [http://www.mymopar.com/downloads/carterafbtuning.pdf Carter AFB Selection and Tuning Guidelines] from Federal Mogul | |
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[[Image:Thermoquad.jpg]] | [[Image:Thermoquad.jpg]] | ||
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[[Category:Carburetors]] | [[Category:Carburetors]] | ||
[[Category:Engine]] | [[Category:Engine]] | ||
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