? Valvetrain Geometry ?

To determine how long your pushrods need to be roll the engine over to where the cam lobe your testing is at the base circle and install the adjustable pushrod (shortened all the way up to start so your not compressing the lifter). Then slowly lengthen the adjustable pushrod until it won't spin easily with 2 fingers. In other words take out all the free play and your at zero lash. Remove the pushrod and measure it and add .030-.050 for preload and that's how long you need them. If your block has never been square decked you might want to measure all 4 corner cylinders and take an average. Hopefully that's clearer than mud.