don't recall if my 228 had that insulator or not - the 235's all do
considering that piece is actually called the carb "insulator", I'd expect it has to do w/ keeping an even temp in the carb body as Jim sez - I figger if GM put'em there it was because they thought spending the extra money was necessary for whatever reason, so I've never tried not having it there - definitely wasn't a "spacer" to take up the slack on long studs, as they would have just put shorter studs in - no wasted $$$$$$$$ on these ol trucks
OTOH I've never seen reference in any troubleshooting list to problems caused by not having one - prolly cuz they knew nobody'd be goofy enuff to leave it out!
Bill
