HERCULES QXLD3 SPECIFICATONS

The information contained in this document has been derived from the following sources:

1) Operation and Maintenance Manual for QX Series Engines (1956) Hercules Motors Corporation, Canton, Ohio.

2) “A New Standard of Excellence: Diamond T Improved Super Service Engine” (undated brochure), Diamond T Motor Car Company, Chicago, Illinois.

3) “Motor’s Truck Repair Manual” (1948) 2nd edition, Motor, New York, New York.

4) “Motor’s Truck and Tractor Repair Manual” (1951) 4th edition, Motor, New York, New York.

5) “Suggestions for the Care and Operation of Diamond T Trucks” (undated) Diamond T Motor Car Co., Chicago, Illinois
When different specifications are given, I indicate both specifications with the source.

MAJOR ENGINE SPECIFICATIONS for HERCULES QXLD3 ENGINE

Cylinders: six
Bore and stroke: 3 7/16” x 4 1/4″
Displacement: 236 cubic inches
Compression Ratio: 6.5 to 1
Torque: 190 ft. pounds @ 1400 RPM
Horsepower: 91 bhp @ 3200 rpm
Rotation: clockwise, looking at cranking end
Firing Order: 1-5-3-6-2-4
Block, material: Nichrome iron

LUBRICATION

Forced feed gear pump
Pump capacity: 4.9 gallons per minute
Oil pan capacity: 6 quarts
Oil Filter: Purolator L30034 or Wix 51006

MISCELLANEOUS

Timing drive: Helical gears

Water-pump type conventional

Pump capacity: 50 gal. Per minute

Air-cleaner: Oil bath

Engine mounting: Cushion-cradle

CRANKSHAFT AND MAIN BEARINGS

No. of bearings: seven

Bearings, type: precision (insert type)

Bearing Length:

Front 1 1 5/16”
Center 4 1 15/16”
Rear 7 1 15/16”
Int. 2, 3, 5, 6 1 7/32”

Overall bearing length: 10 1/16”

Journal hardening: Tocco

Journal Diameter:

Standard: 2.497-2.498”

.020” 2.477-2.478”

.040” 2.457-2.458”

.060” 2.437-2.438”

Main Bearing Clearance:

Motor’s Truck Repair Manual gives a clearance of .0015-.002”

The Hercules Operation and Maintenance Manual gives the following clearances:

Babbitt lined shell: .002-.003”
Hi-lead bronze shell: .0035-.004”

Crankshaft thrust clearance: .002-.004”

CONNECTING ROD and CONNECTING ROD BEARINGS

Connecting Rod material: heat treated nickel chrome molybdenum steel

Journal Diameter:

Standard: 1.987-1.988”
.020” 1.967-1.968”
.040” 1.947-1.948”
.060” 1.927-1.928”

Rod bearings, type: Precision (insert)

Connecting Rod bearing clearance:

Motor’s Truck Repair Manual gives a clearance of .0015-.002”

The Hercules Operation and Maintenance Manual gives the following clearances:

Babbitt lined shell: .001-.0015”
Hi-lead bronze shell: .0015-.002”

Connecting rod side clearance: .005-.010”

CAMSHAFT

Camshaft Journal Diameter: 1 ¾”

Length of bearings:
Front and rear: 1 1/32”
2 and 3: 9/16”

Camshaft bearing clearance: .0015-.0025”

Camshaft gear back lash to crankshaft: .000-.002”

Oil pump gear back lash to camshaft: .008-.010”

VALVE DATA

Valve arrangement: L-head

Inlet valves: 1 ½” Nichrome Steel

Exhaust valves: 1 ¼” Aust. Al. steel

Valve seat diameter – exhaust 1 ¼”

Valve seat diameter – intake 1 3/8”

Face of valve seat – exhaust 3/32 – 1/8”

Face of valve seat – intake 3/32 – 1/8”

Valve stem clearance in guide:

Motor’s Truck Repair Manual gives a clearance of .001-.0015”

The Hercules Operation and Maintenance Manual gives a valve stem clearance of .002-.0025”

Push rod or tappet clearance in guide: .00075 – .001”

Valve tappet clearance:

Intake (running, hot) .008”
Exhaust (running, hot) .010”

Valve seat angle degrees (exhaust and
intake): 30 degrees

Average valve spring pressure: 41 lbs. @ 1 9/32 ”

PISTONS AND RINGS

Piston material: aluminium alloy

No. of rings: three

Piston pins: 7/8” carburized

Piston ring gap: .015-.020”

Piston ring land clearance – top: .0035-.005”

Piston ring land clearance – other rings: .0015-.003”

Piston pin clearance (aluminium piston): hand push fit

Piston Clearance (for aluminum pistons):

Motor’s Truck Repair Manual gives a piston clearance of .0025”

The Hercules Operation and Maintenance Manual gives a piston clearance of .003-.0035”

MISCELLANEOUS CLEARANCES

Bellhousing clearance on chamfer: .012-.025”

Accessory or water pump shaft end thrust: .002-.003”

Idler bearing (shaft) clearance: .00075-.001”

TORQUE WRENCH TENSION:

Foot pounds

Cylinder head screws – with washers (all) 100

Cylinder head screws (8-10-12-14-15-17-18-20-22-24) 80

Cylinder head screws (all others) 90

Cylinder head stud nuts 60

Connecting Rod bearing caps: 39

Main bearing caps (front and intermediate) 70

Main bearing caps (center and rear) 60

Prepared by: Allan Garber
10914 – 125 Street
Edmonton, Alberta
Canada
T5M 0L6

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