Hughes rockers

You would only use shims that would lift the shaft upward if you cannot obtain a proper wipe pattern with the roller over the valve stem by using the rocker adjuster and pushrod. Or in a case where the spring retainer interferes with the rocker. I fortunately didn't have to do this and I had a zero deck block, roller cam, and RHS heads. Some folks may have different results with different combos, that's why we take measurements. You MUST use a solid checking lifter that you can adjust for the estimated preload you wish to run on your hydraulic ones. For example, take the lifter you wish to install and measure from the bottom of the lifter to the bottom of the cup (you can use a small ball bearing and deduct the diameter of the ball from the overall measurement) And then deduct the recommended lifter preload from that total. Set the adjustable checking lifter to this measurement (you can also use the ball to help set the measurement); use an adjustable pushrod and set your rocker adjuster with a couple threads showing on top of the nut to start. Put a bit of grease or even take a sharpee and "paint" the top of the valve stem. With the cam on base circle, take the slack out of the pushrod to tighten everything up without moving the valve (you should have a dial indicator on the spring retainer in the same linear path as the valve stem) Now roller the engine over to make the pattern. Adjust the rocker adjuster 1/4 - 1/2 a turn each time and repeat until the pattern is as centered as possible and you obtain the maximum valve lift possible. Now check the other valves to see if that pushrod length works for all valves. Takes a long time and patience, but is totally worth it, you will notice that an improper setup robs valve lift. This is how to find the perfect pushrod length, or as perfect as it will get with our geometry. All limitations should be included in the instructions from hughes or on their site.