How to rebuild automotive carburetors
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===Secondary vacuum chamber=== | ===Secondary vacuum chamber=== | ||
| − | On carbs that have a vacuum operated secondary, the secondary vacuum chamber is important. | + | On carbs that have a vacuum operated secondary, the secondary vacuum chamber is important to the function of the carb. It should supply only as much air/fuel as the engine needs, but if the calibrations are not correct, the engine may get too much or not enough. |
| + | [[File:Sec spring selection.jpg|thumb|400px|Secondary vacuum chamber spring selection]] | ||
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| + | The opening rate and opening point is controlled in large part by the secondary vacuum spring. There are several springs available from Holley and others that allow the camber opening rate/point to be tailored to the vehicle's needs. | ||
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| + | [[File:Qc vac holley.jpg|thumb|400px|Quick change lid for the secondary vacuum chamber]] | ||
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| + | Quick change vacuum chamber lids have been developed that allow quick, easy secondary spring changes. They are well worth the money if any serious tuning is going to be done. | ||
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| + | [[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 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. | ||
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