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Accelerator Pump set-up

2288 Views 3 Replies 2 Participants Last post by  Bobalos
I found this on a tech website....any suggestions or comments?

Drag racing calls for a slightly different approach. For the hardest starting line launch with a foot brake, the pump lever override spring should be adjusted so that fuel starts to discharge through the nozzle at an engine speed lower than launch RPM. If a car leaves the starting line at 5000 RPM, the pump shot should begin at 4700-4800; an 1800 RPM launch calls for the accelerator pump shot starting at 1500. The key is to have no slop in the accelerator pump system at starting line RPM, so that the pump shot is not “used up” below that RPM. Although adjusting the accelerator pump as described will create a lot of slop in the pump linkage at idle, (and may produce a stumble when driving in the pits) a car will leave harder. Drag cars equipped with a stick shift or transbrake, where starting line launch is accomplished with the carburetor wide open, requires adjusting like an oval track application.

I have a launch bog that is causing my 60 ft. to suck really bad. Any suggestions?
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I have the same problem, rather than actually fix the car I just hit the kit out of the hole, takes the dead spot RIGHT out. LOL.

Actually I had heard that the other day & it does make some sense. If I have to mash on the gas to get the car to stall up on the converter, then by the time I get to launching it, there is no pump shot left. SO...... putting some slack into it does make some sense, so I get my pump shot back. I would think though.......... depending on how far I have the throttle open already to stall it up, that I would not need as much pump shot as if I was @ idle, because its already working on the main jets. I am fixing to take the bottle back out of the car & do some carb tuning, I will let you know what I find. I have a WBO2 that Im gonna get working (if it kills me), so I should have some datalogs to go with it.

Thanks Bob,
I am going to test this weekend and I am going to try it. Made changes to the motor and trans but left the carb alone from last year. Good luck.
Good luck, I wont be able to go out for another couple of weeks. time for me to get my stuff together & get that data logger & WBO2 working right.

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