This is a 1952 MG TD. It came to us with an overheating problem and carburation issues, among other things. Let it be known that this car came straight from a reputable place with a fully rebuilt motor, and a beautiful job at that. However, why would people painstakingly rebuild this motor and leave the old oil pump as well as the old water pump.
The oil pump and water pump are the most important components of any engine, and it should be a rule of thumb to purchase these components new and replace them when rebuilding a motor. This will not only save a technician’s time investment on an engine, but also protect the financial investment of the customer.
When motors are rebuilt, they are taken apart completely and it is important and responsible to advise customers of optional replacement of old parts for new ones, for better performance. Commonly, classic car owners, wanting to save some bucks, end up spending more money because of not making the right decision for their car at the right time.
Water pump and oil pump replacement, carburation, valve lash adjustment
Now, in order to properly replace the water pump on the MG TD, the radiator must be taken out so that you can have easy access to all the bolts and the fan in place. The pump cannot just go in without adjustment because it has specific tolerances that techs must adhere to. Also, the pump comes with a graphite seal that must be spanned dried in order for the surfaces to mate. Failure to do so will signify in a pump that leaks and the mating surfaces ruined. Be clear to read instructions prior to installation.
This TD was equipped with a twin 1 inch SU set-up. The most common problem with the SU is the lack of oil in the slide. This signifies the car running under a fuel starve mode because the slide is there to create the necessary negative pressure so that the fuel can be drawn from the fuel bowl, though the main jet and the RPM range is controlled by the needle, which is attached the slide. Another aspect of the SU that is critical is for the carburetors to work in sync. In order to synchronize your carburetors you need to have the car at idle and sustain it. This is basically making sure that both carbs have the same degree of opening in their butterflies. This is best achieved with a synchronizer tool. The TD enjoys an extremely low idle due to their factory timing setting of 0 degrees, also know as TDC. This setting brings the idle down between 500 and 600 RPM, anything above that is not factory recommended. You must domesticate the SU to achieve this low idle speed. The fuel/air mixture that the TD likes at idle is richer than the usual 14.7. The TD enjoys 13.5 because of their lack of advance in the ignition. Do not attempt to advance the ignition because this will signify in an overheating problem. You could sustain 10 degrees of initial advance, but that will mean resetting everything to run on super expensive fuel and the horsepower gains are minimum, therefore making it not cost effective.
Valve Lash Adjustment
The valve lash adjustment should be done using the brother system. Remove the valve cover with about 10 yards of space to move the car back and forth. Put the car on 4th gear and push the car until one of the valves is fully depressed. Now, it would either be intake or exhaust, it does not matter. Once the valve is fully depressed you put your filler gage on the valve next to it, on the same cylinder. The factory recommends doing this with the carb hot at 0.2. However, to make a little bit more valve lift and less valve train noise, we recommend doing it at 0.9 with the car cold.