| Type | Gasolene, with flanged dry-type cylinder liners Note: later engines are parent bores, no liners. Unknown changeover point. |
|---|---|
| Cylinder Arrangement | In-line 6, vertical |
| Bore | 3.875in (98.42mm) |
| Stroke | 4.250in (107.95mm) |
| Displacement | 300.7 cu.in (4927cc) |
| Compression Ratio | |
| R2001-R10740 | 6 to 1 |
| RL10741-RL20635 | 6.1 to 1 |
| RL20636-RL32999 | 6.5 to 1 |
| RL36321- | 6.6:1 |
| Net Flywheel BHP | |
| R2001 - R10740 | 94hp at 3000rpm |
| R10741 - RL36320 | 97.8hp at 3000rpm |
| RL36321 onwards | 114 at 3200rpm |
| Net Brake Torque | |
| R2001 - R10740 | 220 lb.ft (298Nm) at 1200rpm |
| R10741 - R36320 | 220 lb.ft (298Nm) at 1000rpm |
| RL36321 onwards | 222lb.ft (301Nm) at 1200rpm |
| Loss of efficiency at altitude | |
| 5000 ft | 20% |
| 10000 ft | 37% |
| Intake | .006in (.15mm) |
| Exhaust | .013in (.35mm) |
| Intake | .010in. (.25 mm) |
| Exhaust | .010in. (.25mm) |
| Crankshaft Gear | 31 teeth |
|---|---|
| Camshaft Gear | 62 teeth |
| Helix Angle | 24° 15' |
| Backlash | .0005 to .0045in (0.012 to 0.114mm) |
| Timing Gear Bore Dia | 1.2755 to 1.2763 in (32.398 to 32.418mm) |
| Valve Timing Engines RL2001-32999 | Intake | Exhaust |
|---|---|---|
| Valve Opens | T.D.C. | 38° before B.D.C. |
| Valve Closes | 42° after B.D.C. | 4° after T.D.C. |
| Valve Timing Engines RL33000 onwards | Intake | Exhaust |
| Valve Opens | 10° before T.D.C. | 40° before B.D.C. |
| Valve Closes | 45° after B.D.C. | 15° after T.D.C. |
| Nominal Valve Lift Engines R2001-RL32999 |
.408 in 10.36 mm |
.408 in 10.36 mm |
| Nominal Valve Lift Engines RL33000 onwards |
.390 in 9.91mm |
.390 in 9.91mm |
| Valve Seat Angle | 29° | 44° |
| Valve Face Width | ||
| Engines RL2001-23227 | 0.141 in (3.58mm) | 0.156 in (3.96mm) |
| Engines RL23228 onwards | 0.141 in (3.58mm) | 0.121 in (3.07mm) |
| Valve Overall Length Engines R2001-RL32999 |
5.548 to 5.578 in. 140.9 to 141.7mm |
5.586 to 5.621 in. 141.9 to 142.8mm |
| Valve Overall Length Engines RL33000-RL37667 |
5.718 to 5.748 in. 145.24 to 145.99mm |
5.620 to 5.665 in. 142.75 to 143.89mm |
| Valve Overall Length Engines RL37668 onwards |
5.699 to 5.729 in. 144.75mm to 145.62mm |
5.600 to 5.645 in. 142.24mm to 143.38mm |
| Valve Stem Diameter | .341 to .342 in (8.66 to 8.68mm) |
.340 to .341 in (8.64 to 8.66mm) |
| Valve End-Cap Clearance | N/A | 0.0005 to .0045 in. 0.012 to 0.114mm |
| Valve Stem/Guide Clearance Engines R2001-RL32999 |
.0005 to .003 in. 0.012 to 0.076mm |
.0015 to .004 in. 0.038 to 0.10mm |
| Valve Stem/Guide Clearance Engines RL33000 onwards |
.001 to .0027 in. .025 to .069mm |
.002 to .004 in. .050 to .10mm |
| Approx Free Length | 1-7/8 in 47.625mm |
|---|---|
| Rate | 153 to 163 lb at 1-9/32 in. 69 to 74 kg at 32.5mm |
| Number of Coils | 6 |
| Diameter of Wire | .192 in 4.87mm |
| Length | (Engines R2001-RL32999) 2-13/32 in. 61.12 mm |
|---|---|
| (Engines RL33000-RL36320) 2-51/64 in. 71.0 mm |
|
| (Engines RL37668) Inlet: 2-49/64 in. (70.2mm) Exhaust: 2-51/64 in. (71.0mm) |
|
| Standing Height Above Cylinder Head |
(Engines R2001-32999) 13/32 in. 10.32mm |
| (Engines RL33000-RL36320) 51/64 in.? 20.24mm |
|
| (Engines RL37668 onwards) 49/64in. 19.44mm |
|
| Outside diameter | .6260 to .6265 in. 15.90 to 15.91mm |
| Inside diameter | .343 to .344 in. 8.71 to 8.74mm |
| Diameter | .873 to .8735in 22.17 to 22.19mm |
|---|---|
| Rocker Bush ID | .8745 to .8755in 22.21 to 22.24mm |
| Rocker/Shaft clearance | .001 to .0025 in 0.025 to 0.063mm |
| Grade | Piston Size (Grading point: Top of skirt) |
Liner Bore Diameter |
|---|---|---|
| R | 3.8715 to 3.8720in. 98.336 to 98.350mm |
3.8735 to 3.8740in. 98.388 to 98.401mm |
| B | 3.8720 to 3.8725in. 98.350 to 98.360mm |
3.8740 to 3.8745in. 98.401 to 98.413mm |
| Y | 3.8725 to 3.8730in. 98.360 to 98.375mm |
3.8745 to 3.8750in. 98.413 to 98.426mm |
| W | 3.8730 to 3.8735in. 98.375 to 98.388mm |
3.8750 to 3.8755in. 98.426 to 98.439mm |
In military service, officially, no oversize/overbore pistons were supplied or used. Instead, the liner would be replaced and the correct grading of piston would be then used for the new liner. In the commercial world, however, over-bore pistons up to .030 were available.
| Piston Clearance | .0015 to .0025 in. (.038 to .064mm) |
|---|
| Ring | Width | Clearance in Groove | End Gap in bore |
|---|---|---|---|
| Upper Compression | .0925 to .0933in. (2.349 to 2.370mm) |
.0015 to .003in. (.038 to .08mm) |
.012 to .023in. (.30 to .58mm) |
| Lower Compression | .0925 to .0933in. (2.349 to 2.370mm) |
.001 to .003in. (.03 to .08mm) |
.007 to .021in. (.18 to .53mm) |
| Oil Control | .1863 to .1870in. (4.730 to 4.750mm) |
.001 to .003in. (.03 to .08mm) |
.007 to .021in. (.18 to .53mm) |
| Ring | Width | Clearance in Groove | End Gap in bore |
|---|---|---|---|
| Upper Compression | .09275 to .09375in. 2.356 to 2.38mm |
.0014 to .0034in. 0.036 to 0.089mm |
.012 to .023in. (.30 to .58mm) |
| Lower Compression | .09275 to .09375in. 2.356 to 2.38mm |
.0009 to .0029in. 0.023 to 0.074mm |
.007 to .021in. (.18 to .53mm) |
| Oil Control | .18625 to .18700 in. 4.73 to 4.75mm |
.0010 to .0027 in. 0.025 to 0.069mm |
.007 to .021in. (.18 to .53mm) |
| Diameter | .9998 to 1.0002in. (25.395 to 25.405mm) |
|---|---|
| Length | 3.437 to 3.442 in. (87.30 to 87.43mm) |
| Fit in Piston | Hard hand push-fit through each piston boss, at temperature of 65 to 75°F (18 to 22°C) |
| Clearance in small-end bush | .0002 to .0011 in. (.005 to .028mm) |
| Location | Retained by circlips |
| Length - Centre to Centre | 7.620 to 7.630 in. (193.55 to 193.80mm) |
|---|---|
| Big end bore Diameter |
2.5195 to 2.520in. (64.00 to 64.01mm) |
| Big end bore Length Engines R2001-RL32999 |
1.615 to 1.617in. (41.02 to 41.07mm) |
| Big end bore Length Engines RL33000 onwards |
1.552 to 1.554 in. (39.42 to 39.47mm) |
| Big end bearing Diameter |
2.377 to 2.378in. (60.37 to 60.40mm.) |
| Big end bearing Length Engines R2001-RL32999 |
1.397 to 1.407 in. (35.49 to 35.74mm.) |
| Big end bearing Length Engines RL33000 onwards |
1.242 to 1.252 in. (31.55 to 31.80mm) |
| Diametral Clearance Big end |
.002 to .004 in. (.051 to .10mm) |
| End float Big end |
.006 to .012 in. (.15 to .30 mm.) |
| Small end bush Bore |
1.0004 to 1.0009in. (25.41 to 25.42mm) |
| Limit of connecting-rod twist | .0016in (.04mm) per inch (25.4mm) effective mandrel length. |
| Out of parallelism of big and small ends, Engines R2001-RL32999 |
.0006 in. (.015mm) per inch (25.4mm) effective mandrel length. |
| Out of parallelism of big and small ends, Engines RL33000 onwards |
Small end bore must be parallel with the big end bore in all planes. |
| Fit of bolts in connecting rod & caps | Hand push fit. |
| Main Bearing | Bearing Width | Diameter | Journal Width |
|---|---|---|---|
| No. 1 (Front) | 1.604 to 1.614 in. 40.74 to 41.00mm |
2.752 to 2.7535 in. 69.20 to 69.94mm |
1.824 to 1.832in. 46.33 to 46.53mm |
| Nos. 2, 3, 5, 6 | 1.215 to 1.225in. 30.86 to 31.11mm |
1.495 to 1.505 in. 37.97 to 38.23mm. |
|
| No. 4 | 1.625 to 1.635in. 41.27 to 41.53mm |
1.873 to 1.877in. 47.57 to 47.68mm |
|
| No. 7 | 1.676 to 1.677in. 42.34 to 42.60mm |
1.992 to 2.000in. 50.60 to 50.80mm. |
Editor's note: I am squinting so very hard at the "main bearing journals" values given in the WSM, when compared to the main bearing widths given. That's a big difference!
| Main Bearing | Bearing Width | Diameter | Journal Width |
|---|---|---|---|
| No. 1 (Front) | 1.447 to 1.457in. 36.75 to 37.01mm |
2.752 to 2.7535 in. 69.20 to 69.94mm |
1.791 to 1.799 in. 45.49 to 45.69mm |
| Nos. 2, 3, 5, 6 | 1.058 to 1.068 in. 26.87 to 27.13mm |
1.432 to 1.442 in. 36.37 to 36.63mm |
|
| No. 4 | 1.468 to 1.478 in. 37.29 to 37.54mm |
1.810 to 1.814 in. 45.97 to 46.08mm |
|
| No. 7 | 1.215 to 1.225 in. 30.86 to 31.12mm |
1.710 to 1.720 in. 43.43 to 42.69mm |
| Diametral Clearance - All Mains | .002 to .0045in. (.051 to .115mm.) |
|---|---|
| End Float - Thrust Washers on No. 4 | .002 to .012 in. (.05 to .30mm) |
| Standard | .091 to .093in. (2.31 to 2.36mm.) |
|---|---|
| .003 in. Oversize | .094 to .096 in. (2.39 to 2.44mm.) |
| .006 in. Oversize | 0.97 to .099 in. (2.46 to 2.52mm.) |
| Crankpin length | 1.623 to 1.627 in. (41.22 to 41.33mm) |
|---|
| Sizing | Crankpins | All Main Journals |
|---|---|---|
| Standard | 2.374 to 2.375 in. 60.30 to 60.33mm |
2.749 to 2.750 in. 69.83 to 69.85mm |
| .010 Undersize | 2.364 to 2.365 in. 60.05 to 60.07mm |
2.739 to 2.740 in. 69.57 to 69.60mm |
| .020 Undersize | 2.354 to 2.355 in. 59.79 to 59.82mm |
2.729 to 2.730 in. 69.32 to 69.34mm |
| .030 Undersize | 2.344 to 2.345 in. 59.54 to 59.56mm |
2.719 to 2.720 in. 69.06 to 69.09mm |
| .040 Undersize | 2.334 to 2.335 in. 59.28 to 59.31mm |
2.709 to 2.710 in. 68.81 to 68.83mm |
| Camshaft Journal | No. 1 (Front) | No. 2 | No. 3 | No. 4 |
|---|---|---|---|---|
| Diameter | 2.1360 to 2.1365 in. 54.25 to 54.27mm |
2.0460 to 2.0465 in. 51.97 to 51.98mm |
2.0030 to 2.0035 in. 50.88 to 50.89mm |
1.9730 to 1.9735 in. 50.11 to 50.13mm |
| Length | 1-23/32 in. 43.7mm |
1-1/16 in. 27.0mm |
1-1/16 in. 27.0mm |
1-7/32 in. 30.9mm |
| Camshaft Bearing | No. 1 (Front) | No. 2 | No. 3 | No. 4 |
| Diameter | 2.139 to 2.140 in. 54.33 to 54.36mm |
2.094 to 2.050 in. 52.05 to 52.07mm |
2.006 to 2.007 in. 50.95 to 50.98mm |
1.976 to 1.977 in. 50.19 to 50.22mm |
| Length | 1-7/16 in. 36.5mm |
1 in. 25.4mm |
1 in. 25.4mm |
1-9/32 in. 32.5mm |
| Diametral Clearance | .0025 to .004 in (.06 to .10 mm) |
|---|---|
| End Float - Set by thrust plate | .002 to .012 in. (.05 to .30 mm) |
| Dimension from peak to heel of lobe Engines pre-RL33000 |
1.6213 in. (41.18mm) |
| Dimension from peak to heel of lobe Engine RL33000 onward |
1.6784 in. (42.63mm) |
| Minimum permissible peak to heel Engines pre-RL33000 |
1.586 in. (40.28mm) |
| Minimum permissible peak to heel Engine RL33000 onward |
1.653 in. (41.986mm) |
| 1/2in. stud nuts (3/4 in. AF spanner) |
65 lbf-ft (88N.m) |
|---|---|
| 9/16in. stud nuts (7/8 in. AF spanner) |
75 lbf-ft (100N.m) |
| 5/8 in. stud nuts (15/16 in. AF spanner) |
100 lbf-ft (135N.m) |
| 9/16 stud nuts on manifold side 5/8 in. stud nuts other side |
100 lbf-ft (135N.m) for both sides. |
9/16in. full-studs introduced at Engine No. R42345, prior engines had a stud with a 9/16in. end threaded into the block, and a 1/2in. thread at the upper end.
5/8in. short studs on manifold side introduced at Engine No. R50141 to improve distribution of clamping force, and they use plain nuts without washers. The 7 studs on the rocker side retain plain washers and cap-nuts.
| Minimum | Maximum | |
|---|---|---|
| Cylinder Head Studs | 30 lbf.ft (40Nm) | 100 lbf.ft (135Nm) |
| Crankshaft Main Caps | 65lbf.ft (88Nm) adjust to suit fold-over lock. |
|
| Connecting Rod Big end nuts |
60lbf.ft (82Nm) with oiled threads. | |
| Flywheel Bolts | 70lbf.ft (95Nm) |