MG Car Repair: Damper oil, lean side, engine oil

Question
Can I use any other oil, other than Zenith Damper Oil, for my 1975 MGB Carburetor? Thanks Colin

Answer
Hi Colin,
Yes, you can use engine oil, which I like to use. Some mechanics use transmission fluid.
It is, as it's name implies, a damper or shock. The oil serves three purposes. It lubes the slider, dampens the short pulses the vacuum provided at idle and mainly it restricts the air flow momentarily on a quick throttle opening, thus takes the place of an accelerator pump.
It does this by holding the piston down which speeds up the air flow over the jet thus providing more fuel on a quick throttle opening. Even though it holds the needle down too, the increase air flow over rides that restriction of fuel.
The weight of the oil you use will determine the amount of fuel added.
I found from experience that 20w 40 engine oil works well in the south and you may want to use 10w 20 in the north, especially in the winter.
Your 75 B is very much on the lean side as you can prove by removing the air filter and you will see that the car will just about not run. So this makes it very important that you keep oil in the top pot.
Howard