1988 Suzuki Samurai solid valve lifter noise

There's no lifters in this engine and no hydraulic lash adjusters in the rocker arms. Lash is adjustable but you have to do it manually.

Even though the camshaft sprocket timing is correct, the camshaft has to turn far enough to take up the slack between the rocker arm and the camshaft lobe and valve tip. It takes longer to do that when there is a lot of slack so that in effect makes the valve timing late, just as though the timing belt was off by perhaps 1/8th of a tooth. Late valve timing greatly increases low-end torque and that's why you have dandy performance. That is how the "personality" of an engine is modified for a motor home to help it get going at stop lights. Adjusting the valves to decrease the amount of slack causes the valves to open sooner and that increases high-end torque. The camshafts in police cars may be advanced by one or two degrees to provide increased high-end torque for highway pursuits but it comes at a price. Low-end torque will be sacrificed and a big engine will act like a much smaller engine at lower speeds.

If you have a service manual it will tell you what to adjust the intake and exhaust valves to and whether to do that with the engine warm or cold. There has to be some play so the valve stems have room to expand when the engine warms up. Each rocker arm has a lock nut and an adjusting screw.