Re: Ken's 1937 120 Touring Sedan

Posted by Owen_Dyneto On 2016/5/15 16:00:44

Ken, if at all possible set your idle mixture with the aid of a vacuum gauge reading intake manifold vacuum. You don't simply want the highest vacuum, you want the highest vacuum consistent with the leanest mixture. In practice this means running the idle screw in (leaning the mixture) until those cylinders begin to stumble and then richening it while watching the gauge. As soon as the vacuum ceases to rise, you at the optimum. Then of course do the other venturi, and back to the first for a final check. Avoid the human nature tendency after you've achieved max vacuum to "give it a little extra".

And just as JW says, do this after you've set the idle speed to a comfortable idle. And you may well end up readjusting the idle speed after you've adjusted the idle mixture.