The K&B .61 has been provided with a wide variety of carbs over the years that for the most part do not use second needle type carbs for mid range but instead use a rotating spraybar system. Only those versions with oversize venturi's will require a pump of some sort most have a more reasonable venturi and do not require a pump.

There are two types of Perry/Varsane/Conley pumps. The VP 20 ossilating pump must be mounted on the crankcase in the plane of the crankshaft rotation and torsional impulses from the crankshaft vibrates a little ball in a passage and this provides the pump action. It has no pressure regulator but does have a volumn adjustment by limiting the travel of that bouncing ball.

The other is the VP 30 that requires a pressure tap on the crankcrase and it is the crankcase pressure impulsed that move the fuel. This pump is pressure regulated.

One last tidbit you should perhaps know is that the vast majority of the .61's and the .40's use a single 'Dykes' piston ring. This L shaped ring at the very top of the piston uses combustion gasses to expand the ring to privide for the seal. It does not use spring tension to accomplish this, therefore when the engine is not running it will appear to have little compression.

John