Table of Contents
Advertisement
60
ASSEMBLe- 6U$HIN(,S
FLUSH WITH BOSSES
AS SHOWN
I
/--!~,
I
.
,
I
~A
0.240
22949
.•
-~,;~;"~
I
.7031.± .0005
LINE REAM BUSHING
I
.
~
I
VIEW AA
Figure 17. Assembling Rocker Shaft Bushings.
(9) Stone finish surfaces of rocker boxes for nicks and
scores. Polish surface with crocus cloth.
OO)lf the rocker shaft is excessively loose
in
the cylind-
er head support bosses they may be brought back to stand-
ard size by boring or reaming in line and installing repair
bushings. The center line of the enlarged boss bores must be
9.901-9.911 inches above the cylinder base flange mounting
surface, in order that the reamed bushing bores will main-
tain the same distance. This dimension is important, be-
cause variations in spacing of the rocker axis from the cam-
shaft will change the mechanical clearance in deflated valve
lifter units and may make them inoperative. The minimum
boss wall thickness measured at the edge of the center boss
prior to any reaming and bushing must be 0.240 inch. The
bore surface must be 60 RJ\1S after reaming.(See Figure
17.)
(c) Valve Mechanism.
( 1) Remove nicks and scores from exhaust and intake
rockers and polish finished surfaces with crocus cloth.
(2) Polish valve rocker bushings for slight scores and
roughness.
(3) Straighten push rods which are slightly bent by tap-
ping into proper shape, using a light mallet. Polish ball ends
with crocus cloth. Loose or badly worn ball ends must be
replaced by complete pushrod assembly.
(4) Valve springs which are broken at flat ends cannot
be repaired satisfactorily and, therefore, should be re-
placed.
(5) Remove scores or burrs from valve spring seats by
stoning and polishing.
(6) Polish valve spring seat locks with crocus cloth in-
side and outside diameter.
(7) Stone valves to remove burrs and scores in the lock
grooves and on stem tips. If tips are worn, they should be
dressed with a fine emery wheel to secure a flat surface,
square with valve stem. Replace warped or badly pitted
valves. Use a standard valve refacing machine for condi-
tioning valve contact faces and lap into valve seats.
(d) Crankshaft and Connecting Rods.
(1)
Before Magnaflux inspection, polish journals, crank-
pins and oil seal race. Stone any nicks on finished surfaces.
(2) If threads of any propeller bolt bushing are damag-
ed, drive out old bushing, and draw in a replacement bush-
ing with the rounded side of the head toward the shaft. If
damper pin bushing in shaft or counterweights are worn,
drive out or press out old bushings, and drive or press in
replacements which have been chilled. Be sure to use
COt-
rect bushings.
(3) Plug oil holes with soluble grease or fibre before
Magnaflux inspection. Remove plugs after inspection. Re-
move Hubbard plug before inspection. Install new plug
after inspection (except C145-2H shafts).
(4) Excessively worn shafts must be reground to .010
inch undersize and re-nitrided.
(a) Excessive localized brinelling of the crankshaft
dampener pin bushings can affect propeller blade tip stress-
es. It is, therefore, recommended that at each major over-
haul the pin bushings be inspected and replaced as required.
Only the crankshaft blade bushings are available in oversize.
(b) Inspect in the following Manner :V1easure the inside
diameter of the bushing across points A,B and
C.
Take the
average of A and B and deduct this from C. If the differ-
ence exceeds 0.001 inch, the bushing or counterweight
should be replaced.
B
c
B
Figure 18. Measurement of Dampener Bushing.
1.
The C measurement should be the point of max-
mum diameter, which is generally a point perpen-
dicular
to
the lengthwise centerline of the crank-
shaft.
2.
.\1easurements A and B should be taken at points
approximately 60° either side of point C.
3.
After removing the bushings from the crankshaft
blades, measure the inside diameter of the holes.
Select a replacement bushing which will give an
interference fit of 0.001 to 0.002 inch.
(c) Replacement bushings are available in standard,
0.0015, 0.003 and 0.005 inch oversize on the outside dia-
meter.
(d) A special tooi for removing and replacing these
bushings has been developed by Borrough's Tool and
Equipment
Corporation,2429
North
Burdick
Street,
27
Advertisement
Table of Contents
