B-rad, are the 2 freeze/welch plugs oriented correctly in the rear coolant passages of the cylinder heads? It's hard to tell from the photograph posted but it looks like the convex surface is on the atmospheric side rather than on the pressurized side. I'm not familiar with the assembly details of the Lincoln Y - hope this helps.

64F100 57FAIRLANE500

No idea. Gonna take a look in the manual when I get back out there. Not even sure what I'm looking at

Brad
Sierra Vista Arizona
1954 Lincoln Capri