[spriddle]

Thanks Dave:

Originally Posted by smallblock450sl

No problemo....take the 4 valve cover bolts off and remove the valve cover and remove the spark plug. useing a screwdriver into the spark plug hole, turn the engine over (by hand!) by turning the primary clutch till the piston is at "top dead center" or "TDC". Use a 4 thousanths feeler gauge between the top of the valve stem and the rocker arm addjustment bolt head. If there to tight, the valve can't close, if to loose..you could lose a push rod when reving it up. To adjust, if needed, loosen the 10 mm "jam nut" on the adjuster screw, then ever so slightly, turn the adjuster screw (clockwise to tighten) till there is a "slight drag" on the feeler gauge, then tighten the jam nut and check witthe feeler gauge for tightness. You will need to do this several times, because the "tightening of the jam nut will affect the adjustment. Then, it is VERY important that you turn the engine over (back to TDC) and recheck the settings. I myself usually turn the engine over and check about 5 times to make shure the adjustment is correct. Reinstall the spark plug and the valve cover and give it a run. Good luck