Re: The Duchess Project: 1940 Super 8 Convertible Sedan

Posted by Owen_Dyneto On 2020/12/31 13:19:48

With regard to the automatic choke setting, I'd suggest disregarding the index marks which may no longer be reliable and simply adjusting it so that, with a warm engine at idle, the choke valve is fully open with slight tension holding it in that position.

With regard to the idle mixture screws, easiest to adjust is with a vacuum gauge on the intake manifold, warm engine at idle, choke fully open. What you want to achieve is maximum vacuum consistent with the leanest mixture. So one at a time, open a screw until vacuum no longer increases, then screw it in (leaning the mixture) until the vacuum just begins to drop, and open just a hair. Ditto with the other screw, then back to the first.

If you've got good hearing you can get a decent adjustment without the vacuum gauge by starting with a rich adjustment and then gradually leaning it (screwing in) until you get the faintest indication of the motor begining to falter, the richen a hair and do the same with the other mixture screw. Then back to the first to confirm. Warm engine at idle of course, choke valve fully open.

Gas overflowing the top of the carburetor is either the failure of the needle and seat, a stuck or leaking float, or excessive fuel pressure from the pump, often the consequence of an electric pump.