0339540 JOHNSON CYLINDER HEAD, All 40 models

1. Remove the carbon ridge from the top inside surface of the cylinders with tool (A).2. Turn the crankshaft until two pistons are at bottom center position. 3. Remove nuts (2). Remove rod cap (1). Put pieces of rubber hose or tape on the threads of the connecting rod bolts as protection for the crankshaft.4. Push the piston and connecting rod away from the crankshaft until the piston rings are above the cylinder block. 5. Remove piston (3) and the connecting rod. Keep each connecting rod with its respective connecting rod and piston.
Do not turn the crankshaft while any of the connecting rods are in the engine without the caps installed.
6. Do Steps 2 through 5 for the remainder of the pistons.Install Pistons
1. Put clean engine oil on the piston rings, connecting rod bearings, cylinder walls and crankshaft bearing journals.2. Turn the crankshaft until the bearing journal for the piston to be installed is at bottom center.3. Make sure the piston ring gaps are at least 120° apart on the piston. 4. Use tool (A) and install the piston in the engine in the same cylinder bore from which it was removed. The hole (crater) in the top of the piston must be toward the camshaft side of the engine. For more detail about the installation of connecting rod bearings, see REMOVE AND INSTALL CONNECTING ROD BEARINGS.5. Check the bearing clearances with tool (B).6. Put clean engine oil on the threads of the bolts and contact surfaces of the nuts for the connecting rod caps.
When the connecting rod caps are installed, make sure that the number on the side of the cap is next to and respective with the number on the side of the connecting rod.
7. Put the cap (1) in position on the connecting rod and install the nuts. Tighten the nuts to a torque of 30 3 lb.ft. (40 4 N m). Put a mark on each nut and the end of each bolt. Tighten the nuts 60 5° more.8. Do Steps 1 through 7 for the remainder of the pistons.end by:a) install cylinder headDisassemble Pistons
start by:a) remove pistons 1. Remove the rings from the piston with tool (A).2. Remove the bearings from the connecting rod and connecting rod cap. 3. Remove snap rings (2), pin (1) and connecting rod (3) from the piston.4. See USE OF PISTON PIN BEARING REMOVAL AND INSTALLATION TOOLS, SPECIAL INSTRUCTIONS, Form No. SMHS7295 for more information of removal and installation of piston pin bearings. 5. Heat the connecting rod to a temperature of 350 to 400°F (176 to 204°C). Put 5P8654 Spacer (11) in the base plate. Put the connecting rod on the base plate of tooling (B).6. Put the connecting rod piston pin bearing end in the center of the port assembly of tooling (B). Install pin (7) in the center of the bore for the connecting rod bearings.7. Install 5P8653 Adapter (9). Put the hole in the adapter in alignment with the hole in the base plate of tooling (B).8. Install clamp bar (10) and clamp pin (6).9. Install new piston pin bearing (5) on adapter (9). The old bearing is pushed out by tooling (B) as the new bearing is installed.10. Put 5P8645 Adapter (8) in position as shown with the taper side down. The piston pin bearing joint must be in alignment with the hole in adapter (9) and the base plate of tooling (B).11. Put pusher (4) on adapter (8).12. Use tooling (B) to push the new piston pin bearing into the connecting rod until adapter (8) of tooling (B) makes full contact with the connecting rod surface.13. Remove the connecting rod and the old piston pin bearing from tooling (B).14. Check the piston pin bearing bore diameter after the bearing is installed. The correct dimension is 1.5010 .0003 in. (38.125 0.008 mm).Assemble Pistons
1. Install connecting rod (3) in the piston with the bearing tab groove (slot) on the same side as the hole (crater) in top of the piston.2. Install piston pin (2) and snap ring (1). 3. When old pistons are to be used, clean the piston grooves with tool (A).4. Install the spring for the oil ring. Install the oil ring with tool (B). The gap in the ring must be approximately 180° from the oil ring spring connections.5. Install the compression ring with tool (B). The side of the ring that has the identification "TOP" must be toward the top of the piston. The gaps in the rings must be approximately 120° apart. Compression rings that do not have identification must be installed with the edge that has the bevel toward the top of the piston.6. Install connecting rod bearings.end by:a) install pistons