Radiator Caps

[firedrake1942]

Having seen the rather beautiful 1957 Sage Green convertible for sale and its engine bay, I am now wondering what is the correct radiator car for my car also 1957 . It is shown with the high radiator and with a silver red and blue AC cap. Looking at Ray Newell's bible I can only see the plain silver caps. I am aware that over the years various caps at various pressures were fitted What is the 'right' one ?

[RobThomas]

4 or 7 psi seem to be common. SV engines had 4 psi. Can't be certain about the A-series. Sorry.

Human lungs can generate about 2 psi so upping the rad cap pressure from 4 to 7 is going to generate quite a few leaks if the car isn't up to scratch. Quite a lot of force involved.

[firedrake1942]

Thanks, all new hoses and rad etc. Do you happen to know what it would have left the factory with - aesthetics-wise ?

[ManyMinors]

I would say that the radiator cap in the top picture is closest to the original pattern - and I've never seen anything except a 4lb cap as original equipment although I know some owners who prefer a higher pressure. The cap in the middle of the picture is probably a modern replacement and the AC cap a more "period" replacement.
In my experience, early Minor 1000s did indeed retain the tall header tank of the Series11 cars along with the heater hose coming directly from the bottom of the radiator.
The lovely Sage Green convertible currently for sale has a good many incorrect and later features gained over the years - like so many old cars do - mine included! It looks in great condition but it might not be the best to copy period-correct details from

[firedrake1942]

Ta muchly. I will leave mine alone then !