Ed,

Not to stir the swirl pot, but I thought that it was decided some time back that higher pressures were better than lower pressures.  The higher pressures are supposed provide more margin of safety before a boil-over occurs, permitting a thinner ethylene-glycol solution and enabling the engine to tolerate higher temps before experiencing catastrophic boiling.  So, I’m wondering where this leaves us.  Is it better to run at low (7-8 psi) pressures, or high (28-30psi) pressures? 

Mark S.

I agree, Al, inquiring minds at least like a plausible hypothesis and I think the discussion has led to that.  Perhaps I'll leave the "cup" of air, just for peace of mind {:>)

Ed