Post by Admin on Apr 27, 2019 22:25:02 GMT -5
When I put a Holley (or clone) together, the last order of business is installing/setting the accelerator pump/s for best function. First, I set the accelerator pump arm spring length to 5/8" with the bolt/nut. Next, put the pump arm onto the pivot stud and rest it on whatever installed pump cam you're using. Then, install the accelerator pump diaphragm spring and set the diaphragm in place. Now, sit the housing onto the diaphragm. If necessary, remove the pump arm and BEND THE ARM where it rides against the pump cam, until the at rest setting like above is is close, with no spring compression needed, and little to no slack/slop in the mechanism. Finally, with the idle speed setting/s where they need to be, tighten the spring bolt/nut just until there's slack, and then loosen the spring bolt/nut just until all slack is gone. Setting them this way utilizes the full lift of the pump cam (what dictates how much fuel is sent in), and there's always more than Holley's (minimum (virtually meaningless)) 0.015" clearance specification at wide open throttle so that the diaphragm is not being bottomed out. Open the throttle to wide open throttle and check to see that the diaphragm isn't being bottomed out. Depending on which pump cam, if the diaphragm does happen to be bottoming out, disassemble again to get the arm out of there and bend the cam end of the arm up a bit more and then reassemble and readjust the spring bolt/nut.