I notice with a slide carb ( round on round opening) you get  more of a straight line function of air to fuel ratio as it progressively opens.

With a flat slide on round opening you get 'diminishing returns' ( my term) as you get past half way.

 

I notice that some carbs have eggs shaped openings, I guess that's to even out the percentage of fuel/air mix to percentage of opening and to compensate for the enrichening at higher RPM i.e. more air to fuel at higher rpm at the fatter end (top).

 

I was wondering what was wrong with a square carb - not completely square mind you, but with some roundness to corners say 1/2 diameter.

Wouldn't this provide for a more linier opening to fuel/ air ratio mix OR does this pose other problems such as air flow and drag/ turbulence? 

 

George (down under)

I donated two giant rectangular carbs from R2800 radial engines to the aircraft restoration people at the local airport. Carbs larger than those actually had rectangular butterflies. An old idea, used when huge amounts of air must be metered. Not much of a factor in metering the fuel. Air flows through the booster venturis and is mixed with fuel before it gets to the butterfly shapes.

 

Lynn E. Hanover

 

Lynn E. Hanover