10. What is the proper float setting for Atomic 4 carburetors (early and late model)?

The float assembly should be adjusted so that it lays parallel with the underside of the upper half of the housing, holding the upper half of the housing upside down and sighting along the plate onto which the floats are attached.

We have gone to this "eyeball" method of float adjustment because it is so difficult to describe more precise methods of measurements. The problem is made worse, due to the fact that several different measurements appear in different manuals, as well as within the instruction sheets from various repair kits.

Float settings that result in the float assembly being slightly below parallel in the above check would be in the direction of richness, while settings in which the float assembly is slightly higher than parallel would tend to be leaner.

It's important to note that fuel pump pressure also plays an important role in the ultimate level that exists within the float chamber. Technical folks from Zenith inform us that the recommended float setting (as described above) is based on a maximum of 4 psi from the fuel pump. Fuel inlet pressure to the needle and seat over 4 psi will result in slightly higher float levels (which leads to richness).

We never gotten any indication from Zenith that there is any concern over too little pressure, but in our experience, inlet pressure less than 1.5 to 2 psi will start to give lean indications such as hesitation during acceleration, and/or some power loss at full power. - Updated: November 4, 2003