TR5 PI, GT6 Mark 2,3

These heads had 7/16" studs which were used for the remaining life of the six cylinder cars, and the pushrod guides were an integral part of the castings. Intake port spacing is the same as that on the later TR6, with the intake openings spaced on 2.21 inch centers. On all four types of head the exhaust ports at the manifold face are the same. [True of early GT6/Vitesse flat port head?] Also the valves are the same size, with exhausts measuring 1.26 across the face and intakes 1.44 inches.