Don't quote me on this, but I believe we had this discussion before. The Chevrolet cooling system went to a pressure system (4psi) in the catalog in 1953 and I believe because of this they bumped the boiling point up to 220°.
I had to replace my 1950-212 gauge this summer but all I could find were the 220 gauges. I also switched to a 4lb cap at that time and haven’t had any problems.
Denny Graham
Sandwich, IL
