Project Mudslinger: Block Damage

After cleaning the head, Teal touched all the seats with a grinder and relapped the valves to make sure all the valves were still seating correctly. This is an important step because it is almost impossible not to inadvertently scratch the seats with the brush. Teal also touched up the deck with a horizontal belt sander.

Before grinding the seats, Teal had already measured all the stem heights. After the head had been thoroughly cleaned, he checked the heights again. The intakes were fine, but the exhaust valves were now too tall. Because this is an overhead-valve engine, stem height is critical. Teal ground the exhaust stems slightly to bring them back within tolerance. The extra height also put too little pressure on the springs. This was corrected by using valve locks that held the retainers 0.050-inch lower than the stock locks did.

Johnson's Machine has its own pulley set CNC machined to its specifications, and it's pretty trick. This is the lower pulley (black) with the cam belt pulley sitting on top. The standard setup (this image) requires that the stock belt retainer be used to hold the cog belt on the pulley, and they are often difficult to find. Johnson's (next image) pulley incorporates the retainer, making it impossible to lose. Also, you will notice Johnson's pulley is made for a grooved belt rather than a V-belt. Richard Johnson says dyno tests have proven that the reduction in parasitic friction from switching belts is worth two horsepower on these little motors.