[Purdy Swoft]

I also cut the flange off the model B intake and brazed it back on at the model A angle . The model B intake is a better choice to get the full power of the B carb . Boring out or reaming out the model A manifold runner gives improvement but the runners that connect to the engine are also larger on the model B intake . The top of the model B intake is flat and had an effect on distribution of the mix to the intake valves. If the intake ports are enlarged on the model A block to model B size and used with the B intake manifold you should get nearly a three horsepower increase with the B carb . Another consideration is that two different inside diameter venturis were used with the model B style carburetors . The smaller venturi was used when the B carb was sold as a replacemnent for the model A carburetor after the model A Zenith carbs were discontinued . Both venturis are available but if you want the full effect you will need the larger model B venturi .