There are two insulators in gp-3.726 pn-838983 and pn-605392 that do appear to be reducers. They run from 1937 to 1949 engines and have a note that says they are used in place of the standard insulator to slow down engine. I would guess this was a form of governor to keep from over reving the engine? The ID is 1 5/8" reduced to 1 1/16".
A picture of one of thes with a sleave cast into it would sure help to clear the water a bit!
I wouldn't mind reading that discussion at the Old GMC forum, but I went to the link and it just takes me to the main page. I couldn't find which forum it was on and I just don't have the time to join or read through all the threads of another forum.
Denny Graham
Sandwich, IL
Last edited by Denny Graham; 09/23/2008 2:44 PM.
