One of our most commonly performed MGB head options is changing out the valve hardware for the correct type. In order to fit dual springs and later type valves, the correct valve hardware is needed. The following page describes the differences between these types of hardware.

The meaning of type "A" and "B":

Type "A" or "B" is a reference to the two different types of MGB valve keepers which are listed in the Moss catalog as type "A" for the earlier type and type "B" for the later type. It is a fact that type "A" parts will not interchange with type "B" parts. The following picture shows the two types on their appropriate valves.

The next photo shows the differences between the two types and also the fact that the type "A" keepers require a spring clip to ensure they do not come loose.

Determining the correct retainers:

As noted, the correct spring retainers must be used with the correct keepers. The following photo shows the two factory type dual spring retainers, assembled with their appropriate components.

The final photo displays the most commonly encountered options. Type "A" hardware can be used with dual springs but cannot be used with larger style valves. Type "A" hardware is undesirable in most cases.
Of the type "B" hardware, there are three retainer options shown. Option number one is the factory dual spring type which is our first choice for "Fast Road" heads. Option number two is an aftermarket aluminum retainer and is not our favorite option, but can be used. Option number three is the factory single spring retainer and cannot be used with dual springs. We seldom choose option number three because we feel the single springs are not suited to performance applications.