The Intake and Exhaust Valve (8/4 & 11) clearance is set by the adjustments on the Rocker Arms (8/23 & 24). The adjustments must be made when the engine is at ambient temperature. Using a 13mm wrench, remove the two nuts and gaskets (8/44 & 41) on top of the Valve Cover (8/40). Gently lift the Valve Cover off the Cylinder Head.

Put the Handcrank into the Camshaft and rotate it counterclockwise until you feel hard resistance from compression. Check the gap between the valve stem and the anvil on the rocker with a feeler gauge. There should be a very slight drag with a .006 inch gauge.

If it is not correct, loosen the locknut (8/24) with an 11mm wrench. Adjust the clearance with a screwdriver in the slot of the adjustment screw (8/23). Hold the screw in position while tightening the locknut. Re-check the clearance. Both valves require the same clearance.
 
The valve clearance should be checked every 250 to 300 hours, or annually.

The Heat Exchanger (16/1) utilizes cupro-nickel tubes. They should last for the life of the generator. However, the tubes can become clogged with silt and sea water contamination. To clean the tubes, remove the End Caps and gaskets on each end. Clear the tubes by pushing a stiff rod through them. Do not use a rod diameter greater than 11/64".
 
The Heat Exchanger contains a sacrificial Zinc Insert in a plug (16/2). Examine it when checking the valve clearance and replace, as necessary. The Zinc is a readily available Type 1A.