This table provides detailed specifications to identify various Mini engine heads, including inlet and exhaust diameters, nominal cubic capacity (cc), and their standard fitments in different Mini and related car models. Use this guide to identify the correct head types based on casting numbers and key features.

Additional Information to identify head:

• A+ Head Castings: Despite sharing the same 12G940 casting number, A+ heads have a distinct appearance. They feature a sculptured look with a ‘sunken’ cast finish, replacing the flat area behind the thermostat housing and around the rocker/head stud areas. Introduced with the Metro in 1980, A+ heads can be easily recognized by their color: putrid yellow for small-bore castings and bright red for large-bore ones. The paint finish is notably difficult to remove, even in a chemical tank. A+ heads were also fitted to some late 1275GT models (1979-on).
• MG Metro Turbo: This variant shares the same valve sizes as other non-‘big valve’ 12G940 heads but features 8mm sodium-filled exhaust valves, designed to enhance heat dissipation for improved performance in high-temperature environments.
• Valve and Collet Features: A+ heads typically feature three collet grooves in the valves, and the collets have a 14-degree cone taper. This is different from single-groove collets, which have a 10-degree cone taper, making the parts incompatible. Additionally, A+ head top caps have a raised ridge around the collet hole to secure the collet in place.
• SPi (Single Point Injection) Heads: Easily identifiable by the lack of a heater tap valve port, by-pass hose adaptor, and water temperature sender tapping just below the thermostat housing. These heads are designed specifically for the SPi system, which is simpler and uses a throttle body injection method.
• MPi (Multi Point Injection) Heads: MPi heads, which feature a multi-point fuel injection system, are identified by the absence of the heater tap valve port and water temperature sender hole below the thermostat. They also have three bolt holes drilled/tapped below the thermostat housing for mounting the alternator bracket, which is unique to this head design.