I was running my 21 this weekend with a basically stock Mark IV, 750 Holly double pumper, mechanical advance carb when it went lean at about 3/4 throttle. At least all the plugs are showing lean.
It was Sunday at Parker it looked like Victory At Sea and I was banging it pretty hard when it felt like I dropped a couple of cylinders. Could this cause a float to hang up? Oil temp and water temp were perfect and the plugs look perfect except for looking lean. I didn't have time to try and trouble shoot it before we left.
It still fires right up, idles and made it back to the ramp ok.