How to rebuild automotive carburetors
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[[File:Holley pv stamping1 id.jpg|thumb|left|400px| Holley power valve vacuum rating]] | [[File:Holley pv stamping1 id.jpg|thumb|left|400px| Holley power valve vacuum rating]] | ||
The Holley carb uses a power valve to supply additional fuel when the engine vacuum drops (and presumably the engine load increases). The amount of fuel it supplies is equal to about 7-8 jet numbers. If the rear power valve (if present) is removed, the threaded hole it was in has to be plugged. The jets have to be enlarged 7-8 jet sizes to compensate for the loss of fuel flow it provided. <br style="clear:both"/> | The Holley carb uses a power valve to supply additional fuel when the engine vacuum drops (and presumably the engine load increases). The amount of fuel it supplies is equal to about 7-8 jet numbers. If the rear power valve (if present) is removed, the threaded hole it was in has to be plugged. The jets have to be enlarged 7-8 jet sizes to compensate for the loss of fuel flow it provided. <br style="clear:both"/> | ||
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| + | If you want to check to see if the PV rating is too high and allowing it to open during idle, turn the idle mixture screws all the way in (count the turns so you can return them after the test). Then start the engine. If the engine won't idle, the power valve is not open. | ||
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| + | If you want to check if the PV is open during idle, turn the idle mixture screws all the way in (count the turns so you can return them after the test). Then start the engine. If the engine won't idle, the power valve is not open. | ||
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===Holley idle transfer slot=== | ===Holley idle transfer slot=== | ||
The drawing below shows the transition slot as seen with the carb held upside down. The drawing on the Left shows an overexposed transition slot. Baseline the throttle blades to give a transfer slot that looks like the image below, Right (approximately as long as it is wide): | The drawing below shows the transition slot as seen with the carb held upside down. The drawing on the Left shows an overexposed transition slot. Baseline the throttle blades to give a transfer slot that looks like the image below, Right (approximately as long as it is wide): | ||
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