| Engine |
| Displacement | 4.957 L (302 CID) |
| Number of cylinders | 8 |
| Bore | 92.2 mm (3.629 in) |
| Stroke | 92.7 mm (3.649 in) |
| Firing order | 1-5-4-8-6-3-7-2 |
| Spark plug | 12405 |
| Spark plug gap | 1.25-1.35 mm (0.049-0.053 in) |
| Oil pressure at idle (engine at normal operating temperature) | 69 kPa (10 psi)-103 kPa (15 psi) |
| Oil pressure at 2, 000 rpm (engine at normal operating temperature) | 207 kPa (30 psi)-276 kPa (40 psi) |
| Compression ratio | 11.0:1 |
| Engine weight | 195.5 kg (431 lb) |
| Cylinder Head and Valve Train - All engines except Boss® 302 |
| Combustion chamber volume | 54.5-57.5 cc (3.33-3.51 cu in) |
| Valve stem diameter - intake | 6.015-6.044 mm (0.2368-0.2379 in) |
| Valve stem diameter - exhaust | 6.015-6.044 mm (0.2368-0.2379 in) |
| Valve stem-to-guide clearance - intake | 0.020-0.069 mm (0.0008-0.0027 in) |
| Valve stem-to-guide clearance - exhaust | 0.045-0.094 mm (0.0018-0.0037 in) |
| Valve head diameter - intake | 37 mm (1.45 in) |
| Valve head diameter - exhaust | 31 mm (1.22 in) |
| Valve face runout | 0.05 mm (0.0019 in) |
| Valve face angle | 3 angle |
| Valve seat width - intake | 1.3-1.5 mm (0.051-0.059 in) |
| Valve seat width - exhaust | 1.4-1.6 mm (0.059-0.063 in) |
| Valve seat runout | 0.04 mm (0.0016 in) |
| Valve seat angle | 121/91/61 degrees |
| Valve spring free length - intake | 51.32 mm (2.02 in) |
| Valve spring free length - exhaust | 51.32 mm (2.02 in) |
| Valve spring perpendicularity - intake | 3 mm (0.118 in) |
| Valve spring perpendicularity - exhaust | 3 mm (0.118 in) |
| Valve spring compression force - intake | 650 N |
| Valve spring compression force - exhaust | 650 N |
| Valve spring installed height - intake | 40 mm (1.5748 in) |
| Valve spring installed height - exhaust | 40 mm (1.5748 in) |
| Valve spring installed force - intake | 265 N |
| Valve spring installed force - exhaust | 265 N |
| Roller follower ratio | 2:1 |
| Head gasket surface flatness | 0.025 mm (0.001 in) in any 25 mm (1 in) x 25 mm (1 in) area; 0.050 mm (0.002 in) in any 150 mm (6 in) x 150 mm (6 in) area; 0.1 mm (0.004 in) overall |
| Cylinder Head and Valve Train - Boss® 302 engines |
| Combustion chamber volume | 54.1-57.1 cc (3.30-3.48 cu in) |
| Valve stem diameter - intake | 6.015-6.044 mm (0.2368-0.2379 in) |
| Valve stem diameter - exhaust | 6.015-6.044 mm (0.2368-0.2379 in) |
| Valve stem-to-guide clearance - intake | 0.020-0.069 mm (0.0008-0.0027 in) |
| Valve stem-to-guide clearance - exhaust | 0.045-0.094 mm (0.0018-0.0037 in) |
| Valve head diameter - intake | 37 mm (1.45 in) |
| Valve head diameter - exhaust | 31.8 mm (1.251 in) |
| Valve face runout | 0.05 mm (0.0019 in) |
| Valve face angle | 3 angle |
| Valve seat width - intake | 1.3-1.5 mm (0.051-0.059 in) |
| Valve seat width - exhaust | 1.4-1.6 mm (0.059-0.063 in) |
| Valve seat runout | 0.04 mm (0.0016 in) |
| Valve spring perpendicularity - intake | 3 mm (0.118 in) |
| Valve spring perpendicularity - exhaust | 3 mm (0.118 in) |
| Valve spring installed height - intake | 40 mm (1.5748 in) |
| Valve spring installed height - exhaust | 40 mm (1.5748 in) |
| Roller follower ratio | 2:1 |
| Head gasket surface flatness | 0.025 mm (0.001 in) in any 25 mm (1 in) x 25 mm (1 in) area; 0.050 mm (0.002 in) in any 150 mm (6 in) x 150 mm (6 in) area; 0.1 mm (0.004 in) overall |
| Hydraulic Lash Adjuster |
| Diameter - intake | 12 mm (0.472 in) |
| Diameter - exhaust | 12 mm (0.472 in) |
| Clearance-to-bore | 0.018-0.050 mm (0.0007-0.0019 in) |
| Hydraulic leakdown rate - intake | 0.45-3 seconds (1) |
| Hydraulic leakdown rate - exhaust | 0.45-3 seconds (1) |
| Collapsed lash adjuster gap | 0.35-0.85 mm (0.0137-0.0334 in) |
| Camshaft - All engines except Boss® 302 |
| Lobe lift - intake | 5.963 mm (0.2348 in) |
| Lobe lift - exhaust | 5.488 mm (0.2160 in) |
| Journal diameter | 28.620 mm (1.1267 in) |
| Journal bore inside diameter | 28.682-28.657 mm (1.1292-1.1282 in) |
| Journal-to-bearing clearance | 0.025-0.075 mm (0.001-0.002 in) |
| Runout | 0.04 mm (0.0016 in) (4 places) |
| End play | 0.15 mm (0.0059 in) |
| Camshaft - Boss® 302 engines |
| Lobe lift - intake | 5.963 mm (0.2348 in) |
| Journal diameter | 28.620 mm (1.1267 in) |
| Journal bore inside diameter | 28.682-28.657 mm (1.1292-1.1282 in) |
| Journal-to-bearing clearance | 0.025-0.075 mm (0.001-0.002 in) |
| Runout | 0.04 mm (0.0016 in) (4 places) |
| End play | 0.15 mm (0.0059 in) |
| Cylinder Block |
| Cylinder bore diameter | 92.200-92.220 mm (3.6299-3.6307 in) |
| Cylinder bore maximum taper | 0.013 mm (0.0005 in) |
| Cylinder bore maximum out-of-round | 0.010 mm (0.0004 in) |
| Main bearing bore inside diameter | 72.400-72.424 mm (2.850-2.851 in) |
| Head gasket surface flatness | 0.0254 mm (0.001 in) across any 38.1 mm (1.5 in) square |
| Crankshaft |
| Main bearing journal diameter | 67.481-67.505 mm (2.657-2.658 in) |
| Main bearing journal maximum taper | 0.004 mm (0.0002 in) |
| Main bearing journal maximum out-of-round (circularity) | 0.006 mm (0.0002 in) between cross sections |
| Main bearing journal-to-main bearing clearance | 0.025-0.045 mm (0.0009-0.0018 in) |
| Connecting rod journal diameter | 52.983-53.003 mm (2.086-2.087 in) |
| Connecting rod journal maximum taper | 0.004 mm (0.0002 in) |
| Crankshaft maximum end play | 0.28 mm (0.011 in) |
| Piston and Connecting Rod |
| Piston diameter | 92.161-92.175 mm (3.6283-3.6289 in) |
| Piston-to-cylinder bore clearance (at grade size) (2) | 0.025-0.059 mm (0.0009-0.0023 in) |
| Piston ring end gap - top | 0.15-0.25 mm (0.0059-0.0098 in) |
| Piston ring end gap - intermediate | 0.30-0.55 mm (0.0118-0.0216 in) |
| Piston ring gap - oil control | 0.15-0.45 mm (0.0059-0.0177 in) |
| Piston ring groove width - top | 1.220-1.250 mm (0.0480-0.0492 in) |
| Piston ring groove width - intermediate | 1.220-1.240 mm (0.0480-0.0488 in) |
| Piston ring groove width - oil control | 2.530-2.550 mm (0.0996-0.1003 in) |
| Piston ring width - top | 1.17-1.19 mm (0.0460-0.0468 in) |
| Piston ring width - intermediate | 1.17-1.19 mm (0.0460-0.0468 in) |
| Piston ring-to-groove clearance - top | 0.030-0.080 mm (0.0019-0.0031 in) |
| Piston ring-to-groove clearance - intermediate | 0.030-0.070 mm (0.0019-0.0028 in) |
| Piston pin bore diameter | 22.004-22.010 mm (0.8663-0.8665 in) |
| Piston pin diameter | 21.997-22.000 mm (0.8649-0.8661 in) |
| Piston pin length | 60.7-61.0 mm (2.3897-2.4015 in) |
| Piston pin-to-piston fit (clearance) | 0.004-0.013 mm (0.0002-0.0005 in) |
| Connecting rod-to-pin clearance | 0.003-0.018 mm (0.0001-0.0007 in) |
| Connecting rod pin bore diameter | 22.003-22.015 mm (0.8663-0.8667 in) |
| Connecting rod length (centerline bore-to-bore) | 150.7 mm (5.933 in) |
| Connecting rod maximum allowed bend | 0.038 mm (0.0015 in) |
| Connecting rod maximum allowed twist | 0.050 mm (0.0019 in) |
| Connecting rod bearing-to-crankshaft clearance | 0.028-0.069 mm (0.0011-0.0027 in) |
| Connecting rod side clearance (as assembled to crank) - standard play | 0.325 mm (0.0128 in) |
| Connecting rod side clearance (as assembled to crank) - max. play | 0.500 mm (0.0197 in) |
| (1) Time required for the plunger to leak down 1.6 mm of travel with 222 N force and leakdown fluid in the lash adjuster. (2) Before Grafal coating. |
