BENDIX TU-FLO 750 COMPRESSOR Service Data - Page 13

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2. Install the compression rings (23) in the proper grooves

with the "pip" mark toward the top of the piston. (Refer

to Figure 14.)

Check the ring side clearance of each ring in the piston ring

groove. (Refer to Figure 12.) If the side clearance is too

large, the piston ring groove is worn beyond speciﬁ cations

and the piston must be replaced.

Rotate the piston rings in their respective groove so that

each end gap is at least 90 degrees from the previous

ring's end gap.

Lubricate the wrist pin (22) and wrist pin bushing in the

connecting rod with engine oil. Assemble the upper portion

of the connecting rods and the pistons with the wrist pins.

Insert the wrist pin buttons (28) in the ends of the wrist pin.

Lubricate the pistons and rings with engine oil. Using a ring

compression tool return the piston to the cylinder bore.

Turn the crankshaft so that one of its connecting rod

journals is in the downward, center position. Install

the crankshaft journal bearing segments (38) on the

connecting rod (37) and connecting rod cap (39). Tighten

the connecting rod bolts (40) evenly and torque to 150 - 170

inch pounds. Install the other connecting rod and piston in

the same manner. It is recommended that new connecting

rod cap screws be used.

Before replacing the cylinder head on the crankcase ensure

the correct pistons have been used by turning the crank-

shaft one complete revolution such that each piston moves

to its maximum upward stroke. At the maximum upward

stroke position each piston should move to the top of the

crankcase. If the piston does not approach the top of the

crankcase the piston is incorrect, and if not replaced, could

result in compressor damage.

BASE PLATE OR BASE ADAPTER

Position the base plate or base adapter gasket (20) on the

crankcase and install the base plate or base adapter (21)

as marked before disassembly. Tighten the six cap screws

(22), securing the cast iron base adapter evenly to a torque

of 175-225 inch pounds for base plate or cover in a crossing

pattern after ﬁ rst snugging all 6 screws.

CYLINDER HEAD

Place the cylinder head gasket (19) and cylinder head

on the compressor crankcase and install the six cylinder

head cap screws. Snug the cylinder head cap screws prior

to torquing the cap screws to 300-360 in. Ibs. in a cross

pattern. Retorque the unloader cover cap screws to 170-

225 in. Ibs.

FINAL COMPRESSOR ASSEMBLY

Install all crankshaft keys making certain to support the

crankshaft to avoid bearing damage. Install the crankshaft

nut where applicable. When installing drive couplings or

gears, do not exceed 120 foot pounds torque on the

crankshaft nut.

Use covers, plugs, or masking tape to protect all ports if

compressor is not to be installed immediately. Protect the

ends of the crankshaft against damage by wrapping with

masking tape or friction tape.

TESTING REBUILT COMPRESSOR

In order to properly test a compressor under operating con-

ditions, a test rack for correct mounting, cooling, lubricating,

and driving the compressor is necessary. Such tests are

not compulsory if the unit has been carefully rebuilt by an

experienced person. A compressor efﬁ ciency or build up

test can be run which is not too difﬁ cult. An engine lubri-

cated compressor must be connected to an oil supply line

of at least 15 P.S.I. pressure during the test and an oil return

line must be installed to keep the crankcase drained.

Connect to the compressor discharge port, a reservoir

with a volume of 1,500 cubic inches, including the volume

of the connecting line. With the compressor operating at

2,100 R.P.M., the time required to raise the reservoir(s)

pressure from 85 psi to 100 psi should not exceed 5

seconds. During this test, the compressor should be

checked for gasket leakage and noisy operation, as well

as unloader operation and leakage.

If the compressor functions as indicated reinstall on the

vehicle connecting all lines as marked in the disassembly

procedure.

TU-FLO

750 AIR COMPRESSOR SPECIFICATIONS

Average weight ........................................................... 53

Number of cylinders ...................................................... 2

Bore size ............................................................. 2.78 In.

Stroke ................................................................. 1.87 In.

Displacement at 1250 RPM ............................ 16.5 CFM

CFM Maximum recommended RPM ............ 2,400 RPM

Minimum coolant ﬂ ow (water cooled) at

Maximum RPM ................................................. 2.5 GPM

Minimum RPM ..................................................... 5 GPM

Approximate horsepower required at

1250 RPM at 120 PSIG (naturally aspirated) ............ 3.2

Turbocharge limits

See Compressor Turbocharging Parameters

Maximum inlet air temperature .............................. 250°F

Maximum discharge air temperature ..................... 400°F

Minimum pressure required to unload

(naturally aspirated) ........................................... 60 PSIG