What was found
AIRCRAFT ENGINE STUMBLES, ACCELERATES POORLY IN COLDER TEMPERATURES, PRIMARILY AT TEMPERATURES BELOW +20 DEGREES WHEN ADVANCING POWER, THROTTLE FROM LOWER RPM, APPROX 1000 RPM AND BELOW, TO TAKEOFF POWER. STUMBLE SEEMS TO OCCUR IN THE 900 TO 1200 RPM RANGE. APPLICATION OF CARBURETOR HEAT SEEMS TO IMPROVE PERFORMANCE AND LESSENS THE STUMBLE, DO NOT SUSPECT CARBURETOR ICE AS A FACTOR.