required. Do not pry on contact surfaces. Remove and
(1) Insert feeler gauge (0.007 inch on intake
discard head gasket.
valves and 0.010 inch on exhaust valves) between
tappet adjusting screw and valve stem cap.
(1) Soak cylinder head in SD.
(2) Hold tappet with 9/16 inch end of one
compressed air and clean rags.
tappet wrench, and turn adjusting screw with 1/2 inch
(2) Scrape carbon from inside of combustion
end of second wrench until feeler gauge fits with slight
chamber area with carbon scraper, or use a wire brush.
drag. Repeat for all valves.
Do not scratch surface when scraping.
d. Restore engine to operating condition by
(3) Scrape or brush gasketed surface to
reversing b. and a. above.
remove gasket paste residue.
c. Installation. Reverse a. above, using new
6-78. GEAR COVER.
Tighten head bolts to 100 foot pounds torque.
(1) Remove radiator, disconnect governor to
carburetor control rod hooked to governor lever.
6-76. VALVE COVER. The engine has two valve
(2) Remove governor attaching screws and lift
covers. These covers are removed for valve service, or
governor away from gear cover.
replacement of the gaskets.
(3) Remove hydraulic pump (paragraph 6-29).
(4) Remove starting crank grab and fan drive
(1) Remove tube from rear valve cover to
crankcase ventilating check valve.
(5) If engine is in vehicle, remove front motor
(2) Remove two screws holding each cover in
support screws. If necessary to raise front of motor to
place and lift off valve covers with cover gaskets.
release the front support, use a large block of wood
under front of oil pan so jack will not damage it. The
b. Installation. Reverse procedure in above, using
front support may be removed from the gear cover, if
(6) Remove gear cover attaching screws
6-77. VALVE ADJUSTMENT.
(Figure 6-31) and pull gear cover forward away from the
a. Remove valve covers (paragraph 6-76).
engine. The crankshaft oil seal will pull off the shaft with
b. To the extent necessary to provide
the gear cover. If no gasket or seals are available, use
working room during valve adjustment, disconnect the
care when removing these parts.
following items: (1)
Air duct (at carburetor).
(2) Throttle, choke, and governor linkages (at
(1) Wash and clean the gear cover and fasten
a new gasket to the gear cover with gasket cement.
(3) Fuel line (at fuel pump intake), and fuel
Loosen thrust screw lock nuts and back screws out two
line from fuel pump to carburetor (remove completely).
or three turns.
(4) Fuel pump (remove two capscrews and
(2) Carefully install the oil seal on the
washers, and remove pump).
crankshaft and slide the seal about one inch back on the
c. Crank engine by hand until D-C mark appears at
shaft. If available, use new seal and ring.
hole in flywheel housing. At this time both valves will be
(3) Assemble the gear cover on the seal. Use
open (tappets cannot be turned with fingers) at No. 1
care that the seal properly seats in the groove provided
cylinder, and both closed at No. 6 cylinder or vice versa,
for it in the gear cover.
depending on whether No. 1 or No. 6 piston is in firing
(4) In order to avoid any difficulty with the oil
position. If No. I valves are open, adjust valve clearance
seal sleeve when pushing the gear cover back in place,
on cylinders 3, 2 and 6, then turn the engine one full
loosen the oil pan and allow the front end of the oil pan to
revolution and adjust valves for cylinders 1, 5 and 4, as
drop 1/8 inch to 1/4 inch. Then push the gear cover back
(5) Check to see that oil seal sleeve is
properly located in the oil pan.