its 12mm plate
an btw, how is 6mm *thick* ??
reasons its 12mm:
1 - the plate is intended to be ported to match the throttles and manifold rather than the manifold itself being ported in a large way - there isnt much fat there
2- basically the plate is designed to bolt flush to the manifold, and have stud emerging from it to which are botled the throttles. all the holes thus require counter sinking, some in one direction, some in the other. 12mm leaves sufficient fat for pull out prevention after heavy countersinking.
3 - in several positions the holes holes themselves will be tapped to accept the mounting of heim joint for the linkage arms. the heim joints are 10mm coarse metric and 12mm is a good mounting depth
reason its in 1 piece:
1 - the linkage assembly is designed into the 'bridges' of the plate. the linkage mounts need to be 'fixed' in relation to the throttle locations to prvent error/relative movement of the linkages and throttles.
2 - the way it ended up, several mounting holes affixing the plate to the manifold needed to be deleted from the design to prevent fouling. cross bridging the two halves allows distribution of clamping load from the securing studs, providing reliable tesion and seal of the plate
cheers
ed