From what I have read slightly better performance but you need to hog out your intake manifold or run a Model B intake to realize the increase. Get the late Model B manifold with the vacuum intake in the rear as it, in my opinion, looks better. The Model B engine got an extra 10 hp with slightly increased compression, a better cam, and the larger carburetor venturi.
Changing to the B carburetor without changing anything else will give you about 2 miles per hour more on the hills and 2 miles per gallon overall. These are my estimates based on my experience.
Changing to the B carburetor without changing anything else will give you about 2 miles per hour more on the hills and 2 miles per gallon overall. These are my estimates based on my experience.
Jim,
A couple of more things you need to address with the B carb. The choke on the carburetor will not line up with the Model A choke rod. You will need to elongate the holes for the bolts mounting the carb to the manifold or buy special bolts sold by some of the suppliers that have a step to accomplish this function. Your fuel line will also not bolt right up without modification.
The usual suppliers sell some 5/16 inch bolts that have the threads cut off by the head of the bolt that allow you to turn the carb slightly to line up the choke rod. They also sell a right angle fitting to hook up the gas line. You can also do both yourself. Model B carb is also harder to rebuild.