G'day folks,
The fit took me to do some research on this air filter, and I've got some useful info.
The original 91791 element [Pope stuck with the Clinton part numbers, which helps] was just a simple block of oiled polyurethane foam.
It's described in a 1961 Clinton Service Bulletin - see attached file. There was a later 1964 element version [in Clinton SB18A], which had an attached rubber sealing flange, but I'd think that wouldn't be easy to reproduce.
So to find a suitable piece of foam, first up I'd have a look at some of the older Briggs one-piece foam elements, to see if there's one which can be cut to suit. Alternatively, contact
Uniflow [the makers of Unifilters] to see if they can supply block foam that's fuel-resistant.
