Any time the camshaft or other valve train components are replaced on the Ford big block engine (429 c.i.d. to 460 c.i.d.) the valves require adjustment to set valve lash and pre-load the lifters. This is important to the final overall performance and durability of the valve train. Improper valve adjustment will lead to rapid camshaft and lifter wear, and poor performance from the engine assembly. In extreme cases catastrophic engine failure can occur.
Remove the valve covers by removing the 3/8-inch attaching bolts with a socket and socket wrench. Valve covers that are stuck to the cylinder head can be freed by prying them loose with a large screwdriver. Loosen the rocker arm adjusting nuts, located on the rocker arm stud, that attach the rocker arm to the cylinder head. Remove the spark plugs to make turning the engine easier.
Turn the engine, with a 3/4-inch socket and socket wrench, until the exhaust-valve lifter on the number one cylinder (front cylinder on the left side of the engine) just begins to move up. Adjust the rocker arm to zero clearance. Zero clearance is met when the push rod has a slight drag on it from contact with the rocker arm and lifter. At this point there should be no free play in the rocker arm. Turn the adjusting nut 1/4-turn more to pre-load the lifter.
Turn the engine again until the intake valve lifter on the number one cylinder just stops moving down. Tighten the rocker arm adjusting nut to zero clearance. Tighten 1/4-turn more to pre-load the lifter. Repeat step 2 and 3 on the remaining seven cylinders. Re-check all of the adjustments to verify they are correct, and readjust as needed
Reinstall the valve covers using new gaskets, and tighten the valve cover retaining bolts snugly. Avoid over-tightening the bolt as this will split the gaskets and cause oil leaks. Start the engine, check for leaks and test drive to verify the adjustment. Excessive lifter noise or backfiring indicates misadjustment. Readjust as needed.
