Just distilled water in it right now.
Since winter temps are finally on the way, I'll fire it up again & drain when cold.
Afraid of the heat going out when I'm away , then.....
More news.... when I sent my engine to CA for that (piss-poor) re-build, I "allowed" the guy to talk me out of my block. He said it was/is a date match to some 70 cars (Mustangs). (1970 May 12)
He replaced it with a newer one. What he didn't tell me was it isn't as nice / pristine.
Yesterday I spotted an add for 3 B2 blocks...... and one is my old one !
Don't know how, but I'm going to try & get it back !