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The Place for Model-A Ford Carburetors

Engine won't idle smoothly at 350 to 450 RPM

  • Vacuum leaks at manifold gaskets, wiper line, or throttle shaft.
  • Idling Jet Orifice contains dirt or rust, or is too small.
  • Idle Air Adjust Screw is mis-adjusted or too short, collapsing spring before it seats.
  • Idling Jet Orifice is too large.
  • Throttle Idle Adjustment Screw is mis-adjusted.
  • Upper Casting Idle Jet Passage is restricted to Idle throat port.
  • Upper Casting Air Adjust Screw Passage is restricted to vent hole.

ˆ Top of Page  •  Throttle Assembly  •  Idle Air Adjustment Needle Valve  •  Carburetor Idle RPM and Idle Air Mixture Adjustment  •  Upper Casting Passages  •  Idle Jet