Why Engines hesitate or Stall.

Discussion in 'General Questions' started by Stoltzee, Nov 4, 2012.

  1. Stoltzee

    Stoltzee Member

    All engines are prone to hesitation or stall when you activate the throttle. What happens when the engine is cold is the choke plate opens too much allowing too much air to flow in the cylinders and it dies, or hesitates. On the old Rochester 4 Barrel Quadrajets for GM cars you set the choke with your foot once and turn the key. The choke is only open about a 1/16". As the spring in the choke heats up it gradually allows the choke plate to open wider until choke is not needed, which is still "less than wide open." The plate opens in ratio to the amount of fuel. You will notice that the secondary plate is still fully closed until you turn the throttle enough to activate the secondary jets, and then the secondary plate, (What do they call them now, valves?) Hence the term "Wide Open."
    When I first started my 149F I ran it wide open, but have found that it runs better with a slight choke plate closer. You have to give it a little adjustment at a time until the hesitation dissipates. Of course though air temperature is always changing so........
    Simple concept, but not a simple solution as of yet. Orrr is it, hmmmm...:detective:
    Also setting the valve clearance to .004" intake and .005 exhaust changes the engine response time also giving it a more throatier sound, and quicker acceleration.
    Last edited: Nov 4, 2012