i have a 3×2 intake for a SBC. the carbs are the large base rochester. its very low profile, any info on when/why it was made would be great to know.
The manifold you reference is part number 5254. It was released during the early 1960’s (I do not have an exact date). It was made in order to take advantage of the greater CFM allowed by the large base Rochester 2GC carburetors. Using 3 large base Rochester 2GC carburetors is equivalent to using 5 Stromberg 97 carburetors.