Re: KPack's 1954 Panama

Posted by DavidPackard On 2020/12/7 23:15:18

Kevin; I downloaded one of the WDG data sheets available on this site, and I would say the pointed needle looks like the accelerator pump discharge check valve, "pump check needle' in Carter speak. See part 17-70 on the 728S/SA sheet. It would be installed pointed end down. The attached drawing is for a WCFB, but the concept is the same. When you depress the throttle pedal the accelerator pump begins to push fuel out of the pump chamber . . . the bottom ball check will close, and the upper needle is pushed upward by the flow of fuel. When the accelerator pump has finished the discharge stroke the needle will fall back to its seat by gravity. When you let off the gas the pump rises and the bottom ball opens. The needle, already being on its seat, inhibits air from flowing backwards into the discharge nozzles. Early Carter documentation might show a 'ball check' in the upper position. I think the needle design was introduced in Packard carburetors in 1941. That's the first part that falls out the first time the carburetor is tipped upside down. If all the fact were known, I've completely assembled a carburetor only to have one part left over . . . yep it was the 'little pointed thing'! The accelerator pump won't work well if either check valve is missing or malfunctioning.

The needle in the fuel inlet valve will normally have an undercut where a spring wire clips on and loosely attaches the needle of the float. See part 25-165S on the same sheet.

Bye the way, I've taken a few photos and measurements of the 'ropes' that fit in the trunk between the fender and wheel tub. I think that subject was discussed a while back. If you still need that info I'll post the information.

dp

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