Hi Jonathan. By not paying attention to the installed height of the valves, the valve train geometry has been changed. The rocker tip no longer pivots over the centerline of the valve stem. This will accelerate wear of the valve guide. Grinding the valve or the seat too much will change the volume of the combustion chamber because the valve now sits deeper in the head. Compression ratio is lowered. Because of the shortened pushrods, the valves aren't opening as far which affects cylinder filling. As RPM goes up there is less time to fill the cylinder, plus less compression; the engine runs increasingly rough and with less power/torque. The valves should have all been matched to the worst one or the bad ones replaced. The volume and compression in all chambers/cylinders need to be the same. Normally, a new cam is installed with new lifters unless the cam's profile is verified to be within specs. Hope this helps for the next time. DB Larson ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/web/.