Price per rod - correct length for 8 port head. Larger 6.35mm diameter widening to 8mm centre, giving a javelin type shape to help clearances. 3 piece push rod (2 ends and 1 rod) which are loctited although once fitted the parts cannot displace and many race engine builders originally fitted them without adhesive. This larger diameter improves rigidity which in turn better translates the cam lobe profile at the valve which therefore improves engine performance, particularly where up-rated/stronger valve springs are used.
The head and block push rod ports must be checked for clearance owing to different rocker geometry alignments. Blocks and cylinder heads all differ and can foul on the push rods. Check that the balls of the push rods fit into the cam follower machined seat without fouling block walls to help decide machining requirements.
Rover usually drilled No 1 and 8 push rod holes in the block to 1/2"(12.7mm)to help alleviate geometry problems and it is suggested this same modification is carried out on the remaining holes and a dummy build made to check all clearances.