0437929 JOHNSON SPARK PLUG, Champion, QL78YC

1. Remove tube assembly (1). Loosen hose clamp (3) between the cylinder head and timing gear cover.2. Disconnect air filter indicator tube (2) from the pipe assembly.3. Disconnect water temperature adapter (4) from the housing. Disconnect clips (5) and pull the adapter clear of the cylinder head. 4. Disconnect tube (7) from the ether start aid valve tube.5. Fasten tooling (A) and a hoist to the cylinder head as shown. Remove bolts (6) that hold the cylinder head to the cylinder block. Remove cylinder head (8). The weight of the cylinder head is 120 lb. (54 kg).Install Cylinder Head
1. Inspect the condition of water ferrule and seal (2). Make a replacement if needed. Put water ferrule and seal (2) in position with the adjustment screw of hose clamp (1) toward the top and approximately 45° to the right of vertical (as seen from the front of the engine). 2. Clean the surfaces of the cylinder head and the cylinder block that make contact with each other. Make sure the surfaces are clean and dry. Install a new cylinder head gasket (5) on the cylinder block.3. Fasten tooling (A) and a hoist to the cylinder head. Put cylinder head (3) in position on the cylinder block. If plugs (4) were removed, put 5P3413 Pipe Sealant on the threads and install the plugs in the cylinder head.4. Put 5P960 Multipurpose Type Grease on the threads of all the cylinder head bolts. 5. Install the cylinder head bolts and tighten as follows: a) Tighten bolts 1 through 18 in number sequence to a torque of 60 10 lb.ft. (80 14 N m).b) Tighten bolts 1 through 18 in number sequence to a torque of 110 5 lb.ft. (150 7 N m).c) Tighten bolts 1 through 18 again in number sequence to a torque of 110 5 lb.ft. (150 7 N m).d) Tighten bolts 19 through 22 in number sequence to a torque of 32 5 lb.ft. (43 7 N m). 6. Tighten hose clamp (1). 7. Connect air filter indicator tube (7) to the pipe assembly.8. Connect water temperature adapter (8) to the housing. Connect clips (9) to the cylinder head.9. Install tube assembly (6). end by:a) install exhaust manifoldb) install fuel injection nozzles
HEAD BOLT LOCATION AND TIGHTENING SEQUENCEDisassemble Cylinder Head
start by:a) remove cylinder heads 1. Fasten a hoist and put the cylinder head in position on tool (A). Use adapter plates (1) from tooling (A) to hold the head in place. 2. Put the valve springs under compression with tool (C).3. Remove the locks from the valves.4. Remove tool (C), retainer, spring, washer and valve from the cylinder head. Put identification on the valve as to its location in the cylinder head. 5. Check the valve spring force with tool (B). Spring force must be 35 5 lb. (155 22 N) when the length of the spring force is 1.715 in. (43.56 mm).6. Do Steps 2 through 5 for the remainder of the valves. 7. Remove the valve seat inserts with tooling (D). The valve guides are part of the cylinder head. Measure the bore in each valve guide .75 in. (19.0 mm) from the outside edge on both ends of each valve guide. The bore must be .3745 .0005 in. (9.512 0.013 mm). The maximum permissible bore is .3760 in. (9.550 mm). Valve guides worn more than the maximum specification can be made to the original size by knurling. See RECONDITIONING PROCEDURES FORM NO. REG00867.Assemble Cylinder Head
1. Clean and remove burrs and all foreign material from the valve seat bores. 2. Lower the temperature of the valve seat inserts and install them with tooling (A).
Do not make the diameter of the extractor (part of tooling A) in valve seat insert larger when the insert is installed in the cylinder head.
3. Grind the valve inserts according to specifications given in ENGINE SPECIFICATIONS. 4. Put clean engine oil on the valve stem. Install the valve, washer (3), spring (2) and retainer (1) in the cylinder head. 5. Put the valve spring under compression with tool (C).6. Install the locks on the valve stem with tool (B).
Make sure locks (4) are in their correct position on the valve. The locks can be thrown from the valve when tool (C) is released if the locks are not in their correct position on the valve.
7. Remove tool (C) and hit the valve with a rubber hammer to be sure the locks are in their correct position.8. Do Steps 4 through 7 for the remainder of the valves.end by:a) install cylinder heads