I have tested both my T's to 15psi without any issues.....but the point raised is a valid one if your radiator isn't in first class condition then use a lower pressure.
I emailed Brassworks today and asked them for there thoughts they believe that 7 to 10 psi should be fine.
hope this...
Things I would do:-
Block the left-hand side inlet hose, remove top hose and fit a pressure fitting (use a snap on stile radiator hand pump) and pressure test the system to about 15psi...leave sitting for 10 to 15 minutes the system should not drop pressure.
If pressure is lost you have a leak...
I have run with and without with no noticeable difference, that said if on long runs the water/coolant level is allowed to get low through natural boil off then the system can no longer thermosiphon and will over heat very quickly.
Once over heated the recovery to normal temperature is slow...
Folks,
What conrods do you need to run in cylinders 1 & 4 when a model A crankshaft is installed to allow for the offset and correct central alignment due to the bearing spacing.
cheers lins