Here's an interesting response to the O'Donovan post; 'Old Miracle' used a Binks 'Rat Trap' carburetor, which is strictly a flat-out track carb, with no idle circuit and no slow-speed cutaway. Howard sent these pix from Australia, showing one of these very rare instruments. Looking at the top photo; the carb is bolted onto the intake manifold tube on the left side (the square bolt head for clamping the carb can be seen past the tickle button). The air intake is on the right, and you can see the connection between the float chamber on the left and the main jet which is in the middle of the brass apparatus towards the bellmouth. The wing nut controls a needle on the main jet with effectively varies the size of the aperture, although as this carb is meant for alcohol, not much finesse is involved. The air intake is controlled by a butterfly valve at the bellmout, although instead of rotating around a fixed shaft in the middle of the bore, the valve acts more like a trap door,
being hinged at the bottom. The cable is connected to a small extension on the 'door' - very direct!The design creates something of a 'ram air' effect, being such a long tube, and is suprisingly similar to a Wal Phillips Fuel Injector. Very simple, but apparently for full-bore track work, it was the hot ticket in the 'teens and early '20's.