Holley accelerator pump
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[[File:Hollow shooter.jpg|thumb|400px|left|"Hollow" screw]]If a shooter size greater than 0.038”-0.040” is required, a “hollow” discharge nozzle screw is advised. Above a 0.037” squirter size, a 50cc "REO" pump may also be required, available under Holley P/N 20-11. Make squirter changes in 3-step increments- i.e. if you have a 28, go to a 31, etc. <br style="clear:both"/> | [[File:Hollow shooter.jpg|thumb|400px|left|"Hollow" screw]]If a shooter size greater than 0.038”-0.040” is required, a “hollow” discharge nozzle screw is advised. Above a 0.037” squirter size, a 50cc "REO" pump may also be required, available under Holley P/N 20-11. Make squirter changes in 3-step increments- i.e. if you have a 28, go to a 31, etc. <br style="clear:both"/> | ||
| − | + | Smaller sized accelerator pump squirters will cause the duration of the pump shot to be longer. Because the fuel cannot be compressed, the spring in the accelerator pump lever compresses then this spring pressure continues to supply fuel through the squirter until the spring has extended back to its original length. | |
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An important point should be kept in mind when tuning a double pumper: The secondary accelerator pump must supply fuel for a sufficient time so that the secondary main nozzles can begin to flow fuel to the engine after the secondary throttles are opened. If the nozzles do not start by the time the pump shot expires, bogging will result. | An important point should be kept in mind when tuning a double pumper: The secondary accelerator pump must supply fuel for a sufficient time so that the secondary main nozzles can begin to flow fuel to the engine after the secondary throttles are opened. If the nozzles do not start by the time the pump shot expires, bogging will result. | ||
| − | Also check | + | Also check all used accelerator pump nozzles closely to see if they've been drilled oversize. If a shooter has been drilled out, the number on it obviously will no longer apply. You may have a hard time telling, if they did a good job so a numbered drill bit set or a wire spark plug gap feeler gauge will help determine the exact size. |
| − | Only drill shooters oversize if it's absolutely necessary. | + | Only drill shooters oversize if it's absolutely necessary. For the best ''repeatable'' results use factory shooters. If you find you have to drill a shooter, no big deal, but do yourself a favor and etch the new size onto it so you'll know what it is later on. |
==Resources== | ==Resources== | ||
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