REMOVAL & INSTALLATION
151 Four and 250 Inline Six Cylinder Engines
- Remove the grille. Remove the radiator hoses and remove the radiator.
- Remove the timing gear cover.
- Remove the valve cover and gasket, loosen all the rocket arm nuts, and pivot the rocker arms clear of the pushrods.
- Remove the distributor and the fuel pump.
- Remove the pushrods. Remove the coil and then remove the side cover. Remove the valve lifters.
- Remove the two camshaft thrust plate retaining screws by working through the holes in the camshaft gear.
- Remove the camshaft and gear assembly by pulling it out through the front of the block.
- If either the camshaft or the camshaft gear is being renewed, the gear must be pressed off the camshaft. The replacement parts must be assembled in the same way. When placing the gear on the camshaft, press the gear onto the shaft until it bottoms against the gear spacer ring. The end clearance of the thrust plate should be .001 to .005 in.
- Pre-lube the camshaft lobes with either engine oil or a product such as STP, and then install the camshaft assembly in the engine. Be careful not to damage the bearings.
- Turn the crankshaft and the camshaft gears so that the timing marks align. Push the camshaft into position and install and tighten the thrust plate bolts to 7 ft. lbs.
- Check camshaft and crankshaft gear runout with a dial indicator. Camshaft gear runout should not exceed .004 in. and crankshaft gear run-out should not be above .003 in.
- Using a dial indicator, check the backlash at several points between the camshaft and crankshaft gear teeth. Backlash should be .004-.006 in.
- Install the timing gear cover. Install the harmonic balancer.
- Install the valve lifters and the pushrods. Install the side cover. Install the coil and the fuel pump.
- Install the distributor and set the timing. Pivot the rocker arms over the pushrods and adjust the valves.
- Install the radiator, hoses and grille.
- Remove intake manifold.
- Remove valve covers.
- Remove rocker arm and shaft assemblies, pushrods and valve lifters. Mark parts as necessary and keep pushrods in order for later assembly.
- Remove timing chain cover, timing chain and sprocket.
- Carefully slide camshaft forward, out of the bearing bores. Working slowly to avoid marring the bearing surfaces. Remove camshaft.
- To install, liberally coat the entire cam with a heavy engine oil or a lubricant specially formulated for engine rebuilding. Slowly slide the camshaft into the engine block, exercising extreme care not to damage the cam bearings.
- Reassemble the engine in the reverse order of removal.
- Disconnect the battery.
- Drain and remove the radiator.
- Disconnect the fuel line at the fuel pump. Remove the pump on 1978 and later models.
- Disconnect the throttle cable and the air cleaner.
- Remove the alternator belt, loosen the alternator bolts and move the alternator to one side.
- Remove the power steering pump from its brackets and move it out of the way.
- Remove the air conditioning compressor from its brackets and move the compressor out of the way without disconnecting the lines.
- Disconnect the hoses from the water pump.
- Disconnect the electrical and vacuum connections.
- Mark the distributor as to location in the block. Remove the distributor.
On 1977 and later model Olds engines, remove the crankshaft pulley and the hub attaching bolt. Remove the crankshaft hub. Proceed to Step 19.
- Raise the car and drain the oil pan.
- Remove the exhaust crossover pipe and starter motor.
- Disconnect the exhaust pipe at the manifold.
- Remove the harmonic balancer and pulley.
- Support the engine and remove the front motor mounts.
- Remove the flywheel inspection cover.
- Remove the engine oil pan.
- Support the engine by placing wooden blocks between the exhaust manifolds and the front crossmember.
- Remove the engine front cover.
- Remove the valve covers.
- Remove the intake manifold, oil filler pipe, and temperature sending switch.
- Mark the lifters, pushrods, and rocker arms as to location so that they may be installed in the same position. Remove these parts.
- If the car is equipped with air conditioning, discharge the A/C system and remove the condenser.
- Remove the fuel pump eccentric, camshaft gear, oil slinger, and timing chain. Remove the camshaft thrust plate (on front of camshaft) if equipped.
- Carefully remove the camshaft from the engine.
- Inspect the shaft for signs of excessive wear or damage.
- Liberally coat camshaft and bearings with heavy engine oil or engine assembly lubricant and insert the cam into the engine.
- Align the timing marks on the camshaft and crankshaft gears. See Timing Chain Replacement and Valve Timing for details.
- Install the distributor using the locating marks made during removal. If any problems are encountered, see "Distributor Installation."
- To install, reverse the removal procedure but pay attention to the following points:
- Install the timing indicator before installing the power steering pump bracket.
- Install the flywheel inspection cover after installing the starter.
- Replace the engine oil and radiator coolant.
If equipped with air conditioning, the system must be discharged by an air conditioning specialist before the camshaft is removed. The condenser must also be removed from the car.
Removal of the camshaft also requires removal of the injection pump drive and driven gears, removal of the intake manifold, disassembly of the valve lifters, and retiming of the injection pump.
- Disconnect the negative battery cables.
- Remove the intake manifold and gasket and the front and rear intake manifold seals. Refer to the intake manifold removal and installation procedure.
- Remove the balancer pulley and the balancer. See "Caution" under diesel engine front cover removal and installation, above. Remove the engine front cover using the appropriate procedure.
- Remove the valve covers. Remove the rocker arms, pushrods and valve lifters; see the procedure earlier in this section. Be sure to keep the parts in order so that they may be returned to their original positions.
- Remove the camshaft sprocket retaining bolt, and remove the timing chain and sprockets, using the procedure outlined earlier.
- Position the camshaft dowel pin at the 3 o'clock position on the V8.
- On V8s, push the camshaft rearward and hold it there, being careful not to dislodge the oil gallery plug at the rear of the engine. Remove the fuel injection pump drive gear by sliding it from the camshaft while rocking the pump driven gear.
- To remove the fuel injection pump driven gear, remove the pump adapter, the snapring, and remove the selective washer. Remove the driven gear and spring.
- Remove the camshaft by sliding it out the front of the engine. Be extremely careful not to allow the cam lobes to contact any of the bearings, or the journals to dislodge the bearings during camshaft removal. Do not force the camshaft, or bearing damage will result.
- If either the injection pump drive or driven gears are to be replaced, replace both gears.
- Coat the camshaft and the cam bearings with a heavy-weight engine oil, GM lubricant # 1052365 or the equivalent.
- Carefully slide the camshaft into position in the engine.
- Fit the crankshaft and camshaft sprockets, aligning the timing marks as shown in the timing chain removal and installation procedure, above. Remove the sprockets without disturbing the timing.
- Install the injection pump driven gear, spring, shim, and snapring. Check the gear end-play. If the end-play is not within 0.002-0.006 in. on V8s through 1979, and .002 to .015 in. on 1980 and later, replace the shim to obtain the specified clearance. Shims are available in 0.003 in. increments, from 0.080 to 0.115 in.
- Position the camshaft dowel pin at the 3 o'clock position. Align the zero marks on the pump drive gear and pump driven gear. Hold the camshaft in the rearward position and slide the pump drive gear onto the camshaft. Install the camshaft bearing retainer.
- Install the timing chain and sprockets, making sure the timing marks are aligned.
- Install the lifters, pushrods and rocker arms. See "Rocker Arm Replacement, Diesel Engine" for lifter bleed down procedures. Failure to bleed down the lifters could bend valves when the engine is turned over.
- Install the injection pump adapter and injection pump. See the appropriate sections under "Fuel System" above for procedures.
- Install the remaining components in the reverse order of removal.
Completely clean the camshaft with solvent, paying special attention to cleaning the oil holes. Visually inspect the cam lobes and bearing journals for excessive wear. If a lobe is questionable, have the cam checked at a reputable machine shop; if a journal or lobe is worn, the camshaft must be reground or replaced. Also have the camshaft checked for straightness on a dial indicator.
If a cam journal is worn, there is a good chance that the bushings are worn.