As regards carburetors for the 4AO-84, I have been fiddling with the engine for several years, have flown behind, and ahead of one or two. As has been discovered by many, the stock genny carb has some issues, since it is set up for 3600rpm continuous, and we generally prop the engine to run 3150-3200rpm, static (with a 54x26 Tennessee prop). I finally had the time, and the funds, to try an experiment to get a decent throttle response, and get rid of the aggravating lean-out at the upper end of the throttle travel.
The carb I have been wanting to try is the Kohler #26, for the KT-17/KT-19 opposed twin engine. There is, now, a Chinese aftermarket carb available that can be had for about $25.
The carb has adjustment in the low-end, and the top-end, and a .812" venturi. The smaller venturi adresses the lean-out condition at the upper end of the throttle travel, as it keeps the velocity up over the fuel metering tube.
Here's the kicker: All I wanted was to get a solid, dependable, adjustable carb. What I obtained was the afore-mentioned criteria, AND 200rpm increase.
Not bad, for a $25 investment.
Everett
