[Jethrow]

Thx guys. Actually as I have it plumbed now it is very similar to what you have Leroy, but my issue is that the top point on the radiator header tanks is just a bit higher than the steam tubes and lower than the cap so I have a small air-pocket there.

The taller cap would help me fill right to the top.

And I had already been looking at that site muzza, it is a good one. I did consider the expansion tank but my main issue is a place to actually put it! And unless I was gunna plumb thru the heater circuit like they say, and instead just run it inline with the top hose (or as a bleed from the top hose) then really it seems to offer no more than a taller rad filler neck.

More thinking required for me!

But thx again.