> I am a little confused by the diagram in the Moss catalog which shows two
> rated caps. My car is a 1958 TR3A but has a long-neck radiator. What do I
> really need? A 4 psi or a 7 psi rated cap?
AFAIK, all TR3/A/B were originally fitted with a 4 psi cap. However, if
your heater will stand up to the additional pressure, the 7 psi cap will
give you both slightly better cooling, and more margin before the coolant
boils. I ran my TR3A at 7 psi (but didn't have a heater).
My original drain taps don't seem to have any problem with the extra
pressure, although I did disassemble and clean them, lap the spigot into the
body a bit, and replace the spring on the bottom, as part of the overall
cooling overhaul. Used a smear of Teflon pipe dope to lubricate the spigot
when reassembling too.
Randall
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