Look at your throttle shaft. It's 70 years old, worn to hell and causing a vacuum leak! This is the 97/81 style, but it works with 48 and 40 models if you use the 9526-97 accelerator pump rod. The bushes compress on installation so ream them through (0.278inch) to insure the correct clearance.

Product Reviews for STROM9581K - STROMBERG