Technical Information (MGB 32)
COOLING SYSTEM MODIFICATION
Last Updated 07/29/06
One of the best investments that you can make on improving the integrity of your MGB 63-76 cooling system is the installation of a coolant recovery system. The modification we will be discussing is the installation of a pressurized expansion tank system similar to what is found on the 1977 and later MGB's.
It is ironic that it took the factory so long to consider this type of cooling system improvement because the MG1100 (circa early 1960s) came with this system as standard.
Moving on... If you consider the 3 ways of improving your engine output; i.e., volumetric efficiency, mechanical efficiency and thermal efficiency. Of the three, improving thermal efficiency is the most often overlooked. Many MGB owners are proud of the fact that their vehicles are running so cool, especially in the height of summer. However, running your engine at low coolant temperatures will rob the engine of potential power output.
The MGB cooling system capacity did not change that much over the years (1963-1976 6 US quarts, and 1977 onwards 7 US quarts). I believe these capacities to be more than adequate when other related components are functioning correctly.
Consequently, it is my recommendation that 1963-76 models be updated to include a pressurized cooling expansion tank system as found on the 1977 and later MGB’s.
The main benefit of utilizing such a system is that the cooling system is now integrally sealed from the outer environment. With the knowledge that there are no internal or external coolant leaks present, the MGB owner can be assured that the coolant level will remain constant. However, there are occasions under extremely high ambient temperatures when the expansion tank will not be able to handle the coolant expansion, and in fact may overflow. Fortunately, this is not a very common problem. If this should occur, we see no problem in fitting some sort of plastic bottle, or container, to handle this additional overflow.
Looking back on the various years of MGB production models, we gain an insight as to how the cooling system changes were made by the factory.
Due to increasing exhaust emission requirements over these years, the factory was mainly required to run leaner fuel mixtures and retarded ignition timing, as well as API, Gulp Valve and Throttle Plate Poppet Valves. The leaner fuel mixtures, along with retarded ignition timing, brought about higher combustion chamber temperatures along with a more efficient combustion.
In 1972 yet another major change was made, the 18V low CR 8:1 engine was introduced to the USA market. Back on the “Merry Go Round”. Once again, there is a limit to reducing exhaust emissions by way of lean mixtures and running retarded ignition settings, peak combustions temperatures will eventually lead to high exhaust HC content. Reducing the CR is one way of achieving this.
Image P0003216 below shows the partial kit that British Automotive will supply you. These parts are as follows:
PART # TANK/KIT
Image P0003217 below shows the additional components that you are required to locate and install to make the installation happen. These parts are as follows:
NOTE: Unfortunately, at this time we are not equiped to locate and provide you with these additional parts.
Image P0003214 below shows the entire components required for the successful installation of this kit.
Image P0003165 below shows the complete kit as fitted to a 1967 MGB. NOTE: Installation of an electric fan kit will interfere with the fitting of this kit.
Prior to carrying out the following instructions, we advise having the complete cooling system, including the heater system, flushed. For environmental reasons, we recommend an approved facility for this operation.