Repair 7

How to Install a Cam in a 350 Motor

The camshaft opens the valves in the engine which allows an air fuel mixture to enter the cylinder for ignition, after which the exhaust valve opens to release exhaust gas from the cylinder. The camshaft in a 350 Chevrolet engine has 16 eccentric lobes that when rotated push up on the lifters. The lifter pushes the push rod in back of the rocker arm which is on a fulcrum. The rocker in turn pushes down on the valve stem and opens the valve. One reason to install a new cam is to increase the lobe lift which increases performance and power.

Instructions

Remove the Old Camshaft

1

Drain the engine of antifreeze, by placing a drain pan under the radiator drain valve and open the drain. Remove the top and bottom radiator hose by loosening the clamps. Unbolt and remove the radiator. Most Chevy radiators are held in by two hold down brackets on top of the radiator. Once removed pull the radiator straight up.

2

Remove the water pump from the engine block, by removing the four, 3/8-inch bolts, two on each side located in the front of the engine. Disconnect the heater hoses by loosening the hose clamps.

3

Pull the harmonic balancer off the front of the crankshaft using the special puller. The puller bolts to the same bolt holes that hold the bottom engine pulley to the harmonic balancer. Thread the large center bolt in, to force the balancer off the crankshaft.

4

Unscrew the eight 1/4-inch bolts from the timing chain cover and remove the cover. Pull it off slowly so the seal is not damaged.

5

Align the two dots, one dot on the camshaft, the bigger gear, and one on the, crankshaft, the smaller gear. The dots must be aligned perfect at their closet point. The crankshaft must be rotated to do this. Rotate the crankshaft by threading a bolt into the front end of the crankshaft and turning it clockwise facing the engine or put the balancer on far enough to grip the crankshaft and turn it.

6

Mark the distributor housing and intake with a corresponding mark near the hold down clamp. Remove the distributor cap and make a corresponding mark on the inside distributor housing with the pointer on the rotor button. Unscrew the distributor hold down clamp and pull the distributor shaft straight up from the intake manifold. Be sure to remove the coil wire, vacuum hose, and unplug the distributor from the cowl.

7

Disconnect the fuel line and throttle linkage from the carburetor. Unbolt the intake manifold from the two cylinder heads and remove it. There are six bolts holding the manifold to each cylinder head. Use a big screwdriver to pry the intake up after the bolts have been removed. Sometimes the gasket adhesive glues the manifold to the cylinder heads.

8

Remove the valve covers from the heads. Loosen all the rocker arm nuts on all 16 rocker arms. Begin with number one cylinder, denoted by the first spark plug on the left cylinder head viewed from the front, and remove the push rod and the lifter from the engine. The push rod is under the rocker arm and the lifter is on the bottom of the push rod. The pushrod and lifter must go back in the same exact place they came out of. This must be done for all 16 lifters and push rods.

9

Remove the three small bolts from the camshaft gear, and pull the gear off. Support the timing chain so it does not fall into the small opening of the oil pan at the bottom of the crankshaft.

10

Bolt the camshaft removing tool to the three bolts holes on the front of the camshaft. Pull the camshaft out keeping it as level as possible, rotating it back and forth a bit to help it along.

Install the New Camshaft

11

Coat the camshaft lobes with assembly lube or heavy oil and apply a liberal amount around the bearing rounds of the camshaft. Attach the cam installation tool to the new cam. Caully slide the new cam into the engine rotating it while holding it level as it is pushed in.

12

Remove the cam installation tool. Bolt on the cam shaft gear, using a single bolt and the dowel pin for now. Turn the camshaft until the cam gear dot is in the six oclock position and perfectly inline with the crankshaft dot, which should still be at the very top. Remove the camshaft gear and place the timing chain over the camshaft and crankshaft sprockets while positioning the cam gear alignment with the dowel pin and the three bolts. Install the three bolts. It may take several attempts to get the exact position of the cam gear with the timing chain.

13

Apply lube to the lifters and slide them back in the exact same bore they came out of. Install the push rods back into the same lifters they were in when disassembled. Reposition the rocker arm on top of the push rod and thread the rocker nut a few turns onto the stud. Repeat this until all 16 lifters, push rods and rockers are back in the same exact place they were when the engine was disassembled.

14

Install the timing chain cover over the timing chain, using a new gasket and apply silicone gasket sealer to the oil pan contact area and tighten the screws.

15

Spot a new intake gasket to the cylinder heads and block. Apply a thin layer of silicone gasket sealer to the block gasket strips in the front and back of the block, to prevent oil leaks. Reinstall the intake manifold and bolts. Tighten the manifold bolts from the center out, alternating from one side to the other.

16

Push the harmonic balancer back onto the crankshaft. Be sure to line up the key and the key slot. Screw the bolt into the crankshaft and draw the balancer tight to the shaft.

17

Replace the water pump and radiator by reversing the steps in which they were removed. Also replace the fuel line and throttle linkage.

18

Slide the distributor back into the intake hole and into the oil pump rod slot on the bottom of the distributor shaft. Align the corresponding marks made on the intake and on the inside distributor housing with the rotor button. The distributor will turn just a bit when it slides down into the hole. It is a good idea to turn the rotor button back, counter clockwise, just a bit from the marks so when it slips in and turns it seats just right. Plug the distributor in and reattach the vacuum line.

19

Rotate the engine until the top dead center mark on the balancer aligns to the timing pointer on the timing cover. Push the rocker arms down on the number one cylinder, they should be even if the engine is on the compression stroke and the rotor button should be pointing at the spark plug wire in the cap that corresponds to cylinder one. If not rotate the engine 180 degree back to the same timing mark. With the cylinder on the number one compression stroke tighten both rocker lock down nuts until the push rod can not be freely rotated under the rocker, then tighten the nut another 3/8-inch turn.

20

Adjust the valves on the next cylinder, which is cylinder eight, by rotating the engine until the rockers on cylinder eight are even on top and adjust them. Next rotate the engine so cylinder four has the rockers even and adjust them. Continue this process using the Chevy small-block firing order, in a clockwise direction, until all 16 valves are adjusted.

21

Replace the valve covers on both cylinder banks, ill the radiator and start the engine.