The following pics show an original era aftermarket Simmons cast iron intake manifold for Model A & B Fords. The Simmons Swan intake is an updraft style along the lines of the original Model A, but with a slightly larger bore, and a higher turbulence balance tube. It was originally claimed that this would provide more even charge loading.
Simmons Swan. This is a heavy manifold. Note the carb throat transition from round to square. It also has the original style vacuum port for the windshield wiper. Original Zenith carburetors fit this manifold.
Original Model A style hotspot and exhaust mounting. Large size square runners.
The vertical tube is 1-1/4 inch ID compared to original Model A size of 1-3/16 and original Model B size of 1-5/16 inch ID.
From Ford Dealer & Service Field.
From Ford Dealer & Service Field.