Check out the FAQ on the Moss MGB Supercharger web page.
The 3 main water pump is unique and making the correct drive pulley to fit it would be very expensive as it could only be a small production run.
The good news is that the 5 main water pump can be fitted to the 3 main block, if the opening is enlarged to fit. This can be done with a hand grinder fairly easily. Once done, the later supercharger kit is a direct bolt on, plus you get a bit higher capacity water pump.
We have had a number of customers perform this procedure with no ill effects.
Kelvin Dodd
Moss Motors Team
Kelvin Dodd
Global Sourcing Engineer
Moss Motors, Ltd.
Helpful Links:
Code of ConductFAQsDisclaimer: Working on automobiles is inherently dangerous. Moss Motors, Ltd. is not liable for injury or damage due to incorrect installation or use of their products. All products are sold with the understanding that the safe and proper installation and use of the products is the customer’s responsibility. Follow factory workshop manual procedures and instructions, but use current shop safety standards and common sense. Some tasks will require professional advice or services which Moss Motors cannot provide.