What is the history of changes in the N's radiator cap? The early 9N had the non-pressurized chrome plated cap? Then, they changed to the painted black cap, pressurized?
Were the early painted caps cast or stamped?

I have a couple of caps that are "hollow tailed" & one that has a solid tail. Trying to figure out when the changes occured.

Jeff

Jeff, I think I'm correct is saying the first cap was a 9N-8100 and was cast brass, crome plated and used 1939/41. Sometime changed from brass to a die cast. All had closed tail section with tabs that locked inside radiator neck as the radiators were 14 qt. non press. These were changed to black in 1942, but the non press radiator only lasted another year or so. Then the 2N-8100 cap with outside tabs and open tail came into play......Kelly.

The 9N8100 drawing was changed to painted zinc die casting either in 12/42 or when redrawn in 9/43. Engineering change info sheets would have to be looked up to find out. Then, who knows if the tooling was already made or if there was some lag before any were received. (Sometimes drawings are made after the fact rather than leading, as they should.) The hard red fiber washer, the diaphragm and the hard red fiber gasket were all parts from the Model B car. The cap should not be called zero pressure or no pressure because it actually had a spec on drawing that it had to withstand 10 psi without leaking. This to keep things neat under the hood, at least. This cap is 3.08 inches wide, where the later cap of a styled stamping spot-welded to the pressure-vacuum relief cap is 3.26 wide. I do not have a print of the chromed cap.

Randy, I looked at one of my 14 qt radiators today after I read about the non press 10 PSI cap and the overflow tube is lower in the neck than the cap, so I'm sure your correct when you say clean in the engine room....Kelly.