Update on running hot. My 51 never ran hot, till today. In fact it ran cold, never got much above 150 degrees. I figured it was either the wrong thermostat in there, no thermostat or one that was stuck open.
I was wrong.
There was a thermostat in it, a Delco one rated for 180 degrees. It was installed upside down.
Near as I could figure the water pressure was sufficient to unseat the valve and kept the engine running too cool. The valve was definitely seated when I pulled it.
I swear the mechanic that maintained this car before me was a world class hack. Everything he touched was poorly and incorrectly done.
While I had the coolant drained to change the thermostat I took advantage of it to pull the radiator so I could clean off the timing marks on the pulley and check my timing. It was too tight to do a good job otherwise.
Timing was set to 30 degrees advanced, at idle speed of 550 rpm. Wow.
So now I am running at about 200 degrees, on an 80 degree day. This was with a lot of low speed driving around a parking lot, teaching my son to drive. In a 51 Cambridge with no power anything, three on the tree. He did pretty well though I think I did pick out the smell of clutch.