Autolite 4100 CFM Size
Venturi Size CFM
1.08 480
1.12 600
1.19 670

The venturi size is stamped on the side of the carburetor.

Find parts for your Autolite 4100.

Buy Your Autolite 4100 Carburetor Kit here.

A complete Autolite 4100 rebuild video is available on DVD.

Free Autolite 4100 Manual
Autolite 4100








Download Your Autolite 4100 Carburetor Manual Here

Autolite 4100 1968-69 Carburetor Manual – specific to the 1968-69 model.

Autolite 4100 Instruction Sheet w/Specifications

Watch a video about testing the 4100 check ball.

Need a New Check Ball Weight For Your 4100?
Autolite 4100Unfortunately these are not made anymore, but you should be able to make one without too much trouble. Here are the specifications: 
1. Brass
2. Length .89″
3. Diameter .125 1/8 welding rod should work.
4. Weight: 1 gram – 1 gram=035273 ozs.


Why does my carburetor lose the fuel after sitting

The fuel loss may be due to a bad fuel pump; they have
known to siphon gas out of the carburetor and back into the tank
through bad valves, or into the crankcase through a bad diaphragm.
Gasoline not has a lower boiling point and the ethanol
additive make it even worse. Some carburetors may be experiencing
percolation. After the engine gets hot and is then turned off, the
carburetor gasoline quickly boils out of the carburetor. I have no
magic bullet for treating the ethanol content of the gas other than to
visit  and hope that a gas station selling non-ethanol gas is located near
you. Obviously, anything which can be done to lower engine temperature
will reduce fuel percolation.
The problem may be warped venturi boosters. The fuel level sometimes stands above the base of those boosters, so you can see where it would be advantageous for the venturi and the bowl casting to seal together.

Carburetor Stumbles
Looking for suggestions on a 1963 390 w/4100 Autolite. Car started to
hesitate on start-up acceleration. Totally a new, overnight situation.
Mechanic noted timing slightly off and distributor was loose
(electronic ignition). Car ran better but secondaries had stopped
working. Installed new diaphragm. Solved secondary issue. Acceleration
issue persists, particularly when cold. Have replaced plugs and wires.

  • Made sure the main discharge check ball was installed
    and not leaking. There should be a pin (weight) on top of it. There is also
    an intake check ball (or red check diaphragm) in the pump. Both must be
    present for the pump to work.
  • An insufficient fuel level will cause the pump not to
    work. As I recall, the intake port for the pump is positioned fairly high in
    the primary chamber. Floats should be set to specs (not lower) or the
    pump my not have sufficient draw to operate.
  • Clogged pump nozzles will of course cause a stumble,
    and are more likely to occur with our modern gasohol helping to wash all of
    the accumulated dirt in the fuel system downstream to the carb.
  • If you adjust a Ford 2100 or 4100 by the spec sheet
    which accompanies most carb kits it will invariably have a stumble. You
    instead adjust it by eye and by feel so that the pump arm always keeps
    just a little bit of pressure on the push-rod in the middle of the
    accel. pump diaphragm, even with throttles closed. If you follow the
    instructions, you will always have a gap between the pump arm and the
    diaphragm push-rod . . . guaranteed. Great recipe for a stumble.