Oldsmobile 12721202 LIFTER ASM-VLV

If new lifters are installed, a new camshaft must also be used, and never install used lifters unless the original camshaft is reused.

After removing the camshaft, inspect the bearing journals for wear and damage. Measure the bearing journals with a micrometer to check for excessive wear or out-of-round conditions. Also, check the camshaft lobes for discoloration, score marks, chipped areas, and uneven wear.

If the cam lobe lift is less than specified, you should install a new camshaft.

To determine cam lobe wear, you should first position the number one piston at TDC on the compression stroke. Then, loosen the rocker arm nuts and pivot the rocker arms sideways. Afterward, mount a dial indicator on the engine and position the plunger against the top of the first pushrod. Zero the dial indicator and slowly turn the crankshaft in the normal direction of rotation until the indicator needle stops and begins to move in the opposite direction. Record this figure and repeat the check for each valve.

Store the lifters in a clearly labeled box to maintain their original locations.

To determine the extent of cam lobe wear, position the number one piston at TDC on the compression stroke, remove the valve cover, and loosen the rocker arm nuts to access the pushrods. Then, mount a dial indicator on the engine, position the plunger against the top of the first pushrod, and zero the dial indicator. Slowly turn the crankshaft in the normal direction of rotation until the indicator needle stops and moves in the opposite direction, indicating maximum cam lobe lift. Record this figure and repeat the check for each valve.

A noisy lifter can be diagnosed while the engine is idling by placing a length of hose or tubing near each intake and exhaust valve and listening at the other end. Alternatively, removing the rocker cover and placing a finger on each valve spring retainer can help identify a faulty lifter through the shock felt as the valve seats.

If the lobes are in good condition and the measurements are as specified, the camshaft can be reused.

Disconnecting the engine's electrical connectors from the distributor is necessary to prevent any interference or signals from the distributor that might affect the accuracy of the camshaft lobe lift measurement.