| Subject and Remarks |
All Series |
| Bore |
4" |
| Stroke |
3-7/8" |
| |
| Compression Pressure -- |
|
| At cranking speed (throttle open) |
165 to 185 |
| At 1000 R.P.M |
212 to 230 |
| Compression Ratio |
10.50 to 1 |
| |
| Horsepower -- |
|
| Rated (taxable) |
51.2 |
| Standard Engine developed at 4800 R.P.M |
325 |
| Tri-power Engine developed at 4800 R.P.M |
345 |
| Piston Displacement |
390 Cu. In. |
| Points of Suspension |
3 |
| Torque, Standard Engine, at 3100 R.P.M. |
430 Ft. Lbs. |
| Torque, Tri-power Engine, at 3400 R.P.M. |
435 Ft. Lbs. |
| |
| VALVES, EXHAUST |
|
| Clearance between stem and guide -- |
|
| New limits |
0.0010" - 0.0025" |
| Worn limits, not over |
0.005" |
| Clearance between lifter body and crankcase |
0.0005" - 0.0020" |
| Head diameter, overall |
1.50" |
| Lift |
0.450" |
| Seat angle |
44° |
| Seat width in head |
0.045" - 0.063" |
| Seat concentricity, not over (total indicator reading) |
0.004" |
| Stem, length overall |
4.727" - 4.694" |
| Stem, diameter |
0.3415" - 0.3420" |
| |
| VALVES, INLET |
|
| Clearance between stem and guide -- |
|
| New limits |
0.0005" - 0.0025" |
| Worn limits, not over |
0.005" |
| Clearance between lifter body and crankcase |
0.0005" - 0.0020" |
| Head diameter, overall |
1.875" |
| Lift |
0.450" |
| Seat angle |
44° |
| Seat width in head |
0.045" - 0.063" |
| Seat concentricity, not over (total indicator reading) |
0.004" |
| Stem, length overall |
4.717" - 4.688" |
| Stem, diameter |
0.3415" - 0.3425" |
| |
| VALVE SPRINGS |
|
| Free length |
2.250" |
| Lbs. required to compress to 1.946" (valve closed) |
60 - 65 |
| Lbs. required to compress to 1.496" (valve open) |
155 - 165 |
| |
| ROCKER SHAFT ASSEMBLY |
|
| Clearance between arm and shaft -- |
|
| New limits |
0.0007" - 0.0022" |
| Worn limits |
0.003" |
| Clearance between shaft and bracket |
0.0002" - 0.0017" |
| Shaft diameter |
0.8108" - 0.8113" |
| Diameter of hole in arm |
0.812" - 0.813" |
| Short spring (center) -- |
|
| Free length |
3.73" |
| Pressure (lbs) when compressed to 1.594" |
10-1/2 - 12 |
| Long spring (end) -- |
|
| Free length |
4-31/32" |
| Pressure (lbs) when compressed to 2.219" |
10-1/2 - 12 |
| |
| VALVE TIMING (without ramp) |
|
| Intake opens |
27° B.T.D.C. |
| Intake closes |
75° A.B.D.C. |
| Exhaust opens |
73° B.B.D.C. |
| Exhaust closes |
29° A.T.D.C. |
| |
| CONNECTING RODS |
|
| Bearing Material |
Moraine 400 Alum. |
| Clearance between bearing and shaft -- |
|
| New limits |
0.0005" - 0.0020" |
| Worn limits, not over |
0.0045" |
| Diameter lower end, without bearing |
2.3740" - 2.3745" |
| Length, center to center |
6-1/2" |
| End play of rods on crank pin |
0.008" - 0.014" |
| |
| PISTON RINGS |
|
| Clearance between rings and sides of groove in piston -- |
|
| Compression rings |
0.0022" - 0.0035" |
| Oil rings |
0.0013" - 0.0026" |
| Gap between ends in 4.0000" cylinder -- |
|
| Compression rings |
0.013" - 0.023" |
| Oil rings |
0.013" - 0.023" |
| Number of compression rings |
2 |
| Number of oil rings |
1 |
| Width of compression rings |
5/64" |
| Width of oil ring |
3/16" |
| Diameter at bottom of groove -- |
|
| Oil ring |
3.551" - 3.556" |
| Compression rings |
3.551" - 3.556" |
| Maximum wall thickness -- |
|
| Oil ring |
0.145" |
| Compression ring top |
0.200" |
| Compression ring bottom |
0.200" |
| |
| PISTON PINS |
|
| Clearance between pin and piston -- |
|
| New limits |
0.00005" - 0.0001" at 70°F. |
| Pin length |
3-3/32" |
| Pin diameter |
0.9994" - 0.9997" |
| |
| PISTON AND CYLINDERS |
|
| Cylinder out of round (new or reground limit) -- |
|
| Not over |
0.0005" |
| Taper, not over |
0.0007" |
| Cylinder bore, standard |
4.0000" - 4.0020" |
| |
| CYLINDER CLASS SIZES (10) A to M |
| (Indicated by letters stamped on top of block) |
| Letter |
Cylinder Sizes |
Piston Sizes |
| A |
4.0000 - 4.0002 |
3.9985 - 3.9987 |
| B |
4.0002 - 4.0004 |
3.9987 - 3.9989 |
| C |
4.0004 - 4.0006 |
3.9989 - 3.9991 |
| D |
4.0006 - 4.0008 |
3.9991 - 3.9993 |
| E |
4.0008 - 4.0010 |
3.9993 - 3.9995 |
| H |
4.0010 - 4.0012 |
3.9995 - 3.9997 |
| J |
4.0012 - 4.0014 |
3.9997 - 3.9999 |
| K |
4.0014 - 4.0016 |
3.9999 - 4.0001 |
| L |
4.0016 - 4.0018 |
4.0001 - 4.0003 |
| M |
4.0018 - 4.0020 |
4.0003 - 4.0005 |
|
| |
| Piston material |
Aluminum Alloy |
| Piston skirt diameter -- |
|
| Standard |
3.9958" - 4.0005" |
| Piston skirt diameter - oversize -- |
|
| 0.010" oversize |
4.0085" - 4.0105" |
| 0.020" oversize |
4.0185" - 4.0195" |
| 0.030" oversize |
4.0285" - 4.0295" |
| Piston skirt top clearance |
0.0015" |
| Piston skirt bottom clearance |
0.000" |
| Piston top land diameter, standard |
3.9650" - 3.9680" |
| Piston top land clearance |
0.032" - 0.037" |
| |
| OIL PUMP |
|
| Backlash between drive gears |
0.008" - 0.012" |
| Clearance between pump body and drive shaft -- |
|
| New limits |
0.0010" - 0.0025" |
| Worn limits, not over |
0.005" |
| Clearance between pump body and gears -- |
|
| New limits |
0.003" - 0.005" |
| Worn limits, not over |
0.006" |
| End play in pump gears -- |
|
| New limits |
0.001" - 0.004" |
| Worn limits, not over |
0.006" |
| Oil pump type |
Spur gear |
| |
| CRANKSHAFT AND MAIN BEARINGS |
|
| Clearance, main bearings -- |
|
| New limits |
0.0008" - 0.0025" |
| Worn limits, not over |
0.005" |
| Main bearing caps -- |
|
| Bolt thread diameter |
1/2" |
| Main bearing journal diameter |
2-5/8" |
| Main bearing journals, out of round not over |
0.00025" |
| Main bearing journal length -- |
|
| Front |
0.907" |
| Intermediate |
0.907" |
| Rear |
1.622" |
| Main bearings, material -- |
|
| (Except Rear) |
400M Alum. |
| (Rear) |
Moraine Durex 100A |
| Crankpin diameter |
2.2488" - 2.2493" |
| Crankpin out of round, not over |
0.00025" |
| End play in crankshaft -- |
|
| New limits |
0.001" - 0.007" |
| Worn limits |
0.010"A |
| |
| OIL PRESSURE REGULATOR |
|
| Clearance between valve plunger and housing -- |
|
| New limits |
0.0020" - 0.0035" |
| Worn limits, not over |
0.005" |
| Normal pressure to 30 M.P.H -- |
|
| Minimum |
30-35 lbs. psi |
| Idle (average) |
15 lbs. psi |
| Spring -- |
|
| Free length (approx) |
2.65" |
| Lbs. required to compress to 1.443" |
5.28 - 5.78 |
| Valve opens at |
35 lbs. psi |
| |
| CAMSHAFT |
|
| Chain -- |
|
| Adjustment |
None |
| Length |
23" |
| Make |
Link Belt |
| Number of links |
46 |
| Pitch |
0.500" |
| Width |
11/16" |
| Bearing clearance -- |
|
| New limits |
0.001" - 0.0022" |
| Worn limits, not over |
0.004" |
| Number of bearings |
5 |
| Cam lift |
0.273" |
