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Ferguson Tractor TO-20 Operation and Maintenance Manual

Timing Gears (H)
Both the steel crankshaft and camshaft gears
are available in three sizes-"standard'ยท, "under-
sized" and "oversized". Gears are stamped to in-
dicate size--an "S" for standard, "O" for over-
size and "U" for undersize-followed by a num-
ber to show amount of over or undersize.
The cam gear section of block is also stamped to
indicate original installation with an "S",
"+ ",
or "-", followed by a number to show amount of
over or undersize. When replacing both gears on
block marked
"+
1", use one standard and one
.001-inch oversize. When replacing one gear after
considerable use, the next larger gear should be
used to give a .001-inch tight fit to take up wear.
Rocker Arms (I)
Rocker arms operate on a shaft which receives
oil from rear main bearing and distributes it to
rockers through drilled holes in shaft. They are
fitted with steel-backed, babbitt-lined bushings,
and are assembled with radial groove toward push
rod side. The rocker arm shaft is assembled with
drilled holes facing valve springs.
Valves (J)
Of one-piece construction. the valves have a
45-degree seat-angle.
Note: In reassembling, exhaust valve should just
be closed and intake valve should be ready to
open, with piston at top dead center follow-
ing exhaust stroke.
VALVE ADJUSTMENT
Proper valve adjustment is essential for quiet,
smooth operation and long valve
life.
Check and
adjust as follows :
1. Remove
gas
tank and cylinder head cover.
2.
Remove
spark plugs.
3. Rotate engine with crank until number 1 pis-
ton reaches exact top dead center compres-
sion. (Compression stroke is determined by
extreme pressure from
#
1 spark plug hole
when bole is covered with thumb.)
4. Remove Timing Hole Button Plug (back of
left engine flange) to verify top dead cen-
15
Showing how feeler gouge is used
to
adjust
valve
tappet clearance.
Removing timing hole button plug
ter of
#
1 cylinder. After c-ompression is felt,
turn slowly with crank until graduated line,
indicated by letters "D.C." on fl
yw
heel, 1s
aligned with groove in timing hole.
5.
Set both valves with engine cold at .014.
6.
Engine firing order is 1-3-4-2. Set other
valves by following foregoing procedure.
7. Recheck valves with engine operating at slow
idle speed, using a .013-inch feeler gauge.