[CompClassics]

It is my understanding that the largest side draft available for the side draft application at the time was a 45 mm, unfortunately this size would not provide the needed performance that was needed for the 260 application, nor was it easily enlarged. Instead of reinventing the wheel SAI changed their manifold configuration to utilize the readily available 45 IDM that Maserati was using on their V8 F1 engines that could easily be enlarged from 45mm to 48mm creating the 48 IDM model. Eventually Weber transitioned from sand cast manufacturing to die-cast manufacturing, supposedly with Fords help to increase production volume. The manufacturing change led to 48 IDM being made obsolete and the 48 IDA the new Weber performance carburetor and it has been for decades now.

It is very interesting to note that Jim Hall never transitioned from 48 IDM to 48 IDA Webers and used them all the way into his Can Am program in 1968.