Mercarb Float Circuit

2 Jet Float Adjustment

Float Level Adjustment

  • Bowl gasket in place.
  • Plastic float – measure distance from gasket tolip of free end of float.
  • Brass float – measure distance from gasket to sharp edge of float seam at free end.
  • We set the float to be level, which works great for us.

Float Drop Adjustment

With float hanging freely, measure from gasket surface to lip of plastic float, or bottom of metal float.

Check the float drop to make sure the needle doesn’t fall out, or gets stuck to the side.

The Baffle Around the Float Valve is Missing
This is necessary to operate at 100%, but can be used without it.

Mercarb Brass Float

We no longer carry Nitrophyl Mercarb floats. They were falling apart with ethanol.

Holley 1920 Carburetor Manual
Updated on 11/07/2021

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