Sorry, been gone. Actually, it turned out to be two problems. A plug in the pump had a very slight leak that dripped down onto the upper mouth of the hose, very hard to see. It then leaked from around the hose, so some RTV and reinsertion of the plug fixed that. Its a Stewart Williams high volume pump, and the machining of the plug threads in aluminum causes problems. Also, the lower hose/radiator outlet was leaking. A screwdriver should fix that, but this BBC is so tight in the car that the radiator has to be dismounted and pulled forward so that I can get at it below the fan shroud. PITA for sure.
I'm trying to get the car ready to race, but SAC Raceway got lots of rain last night, so not going today. With this new motor, I need to do some test and tune so the suspension launches straight. I think the first race this year will be mostly a test outing. Famoso does not run enough Test n Tunes, and when they do, it is clogged up with people just out for fun.