Radiator Expansion Tank
The MGA radiator is a 'total loss' system in that water that escapes through the pressure cap due to expansion escapes down a drain pipe to the ground.
All modern cars incorporate expansion tanks that contain this lost water and then allow it to be drawn back into the radiator as the water cools.
Such a system can be incorporated into the MGA using an MGB expansion tank (see photograph).
In this set up, the MGB expansion tank and its retaining bracket were attached to the firewall behind the rear carburettor. A piece of pressure piping attached the expansion tank to the radiator overflow pipe.
The radiator pressure cap was removed from the radiator and fitted with a blanking cap (as shown below), allowing unrestricted water flow between the radiator and the expansion tank.
The blanking cap was a standard cap that had its innards removed and Araldited to make airtight around the remnants of the central shaft. A large rubber washer was inserted to make an airtight seal around the top of the filler neck. A suitable pressure cap was attached to the MGB expansion tank. Note that the MGA pressue cap does not fit the MGB expansion tank - it is too long a reach.