Operating instructions

8-16
8-41. ELECTRICAL WIRING. A 24-volt storage
battery must be connected by a No. 0 stranded copper
cable from its positive terminal to the power terminal
of the starter or starter solenoid. The battery negative
terminal must be connected to the engine or both
battery terminal and engine may be grounded. A
small insulated wire should connect the starter
solenoid coil terminal to a 5 ampere pushbutton
switch. The other switch terminal must be connected
to the engine or both to common ground.
8-42. INSTRUMENTS. The control panel should be
equipped with the following engine instruments:
a. A mechanically driven (counterclockwise, 1/2
engine RPM) tachometer and flexible shaft assembly
is required.
b. An oil pressure gauge and tube connection.
c. An oil temperature gauge and capillary assembly.
d. A cylinder head temperature gauge and wiring.
(See test operating limitations for different maximum
temperatures.)
e. A water manometer with rubber hose connection to
the vacuum pump oil return hole at the rear of the
crankcase.
f. An ammeter connected in the generator or
alternator circuit.
8-43. BREATHER. A substantial hose of 3/4 inch
ID should be securely clamped over crankcase
breather elbow and support so as to lead to a point
above and to the rear of engine.
8-44. FUEL SYSTEM. The test stand fuel system
is to incorporate an auxiliary pump capable of
delivering fuel to and through engine system at a
pressure of 2 to 2-1/2 psi indication on fuel pressure
gauge. Means of determining, by weight, fuel
consumption for given periods of time and at specified
percentage of power should also be included. Connect
stand fuel supply line to upper elbow projecting from
left side of fuel pump shroud. Connect fuel pump-to-
supply tank return line to upper elbow projecting from
right side of fuel pump. Connect fuel pressure gauge
line to the fitting projecting from the center rear of
fuel manifold valve.
8-45. GOVERNOR PAD COVER. A removable oil
transfer tube conducts oil under pressure from the
front main bearing through the crankshaft to the
propeller hub. Crankshafts are equipped with an oil
transfer collar to supply the governor controlled oil to
the crankshaft for use with an oil" controlled
propeller.
When a test club or fixed pitch propeller is used for
testing purposes, the governor pad cover must have an
internal grooved surface to allow the circulating oil to
lubricate the oil transfer collar. The governor pad
cover is not needed if a propeller governor is installed.
8-46. ENGINE TEST AFTER OVERHAUL.
a. After a partial or complete disassembly and repair
of a 285 HP engine, the engine will be tested in
accordance with Table XVII.
b. Run the 300 HP engine according to the schedule
in Table XVIII after a major overhaul.
c. Extend the second period of each test schedule, if
necessary, to raise the oil temperature to 100
o
F.
NOTE
It tests must be conducted in extremely t
cold weather, it may be necessary to
shield the crankcase from the cooling .air
stream, since it takes some heat from the
oil.
d. Take instrument readings at the beginning, in the
middle, and at the end of the full throttle period. Take
one reading during each of the other periods as soon
as conditions have stabilized.
e. Make one check on performance of each magneto
alone at 2100 RPM (Refer to Tables XVII or XVIII.
Clear spark plugs by operating with both magnetos on
for a few seconds between checks.
NOTE
The maximum allowable cylinder head
temperature and the maximum allow- able
oil temperature (Table XVI) must not be
exceeded at any time during the test.
8-47. STARTING PROCEDURE.
a. Open throttle to approximately 900 to 1200 RPM
position.