Table of Contents
1980 Mustang Engine Information – 255 cubic inch V-8 (4.2 L Windsor V8)
The 255 V8
This engine started out its life as a great 302 ci engine, not so after it was de-tuned and modified, it was really sick after the Ford modifications. After modifications, it ended up being a 255 ci engine. Fortunately for mankind, the engine only saw two years of service and was retired. Thank God the 302ci (5.0L) was brought back in 1982.
Following the second oil crisis in 1979, the 302 cu in (4.9 L) “5.0” engine was dropped in favor of a new 255 cu in (4.2 L) V8 due to its better fuel economy. The 255 was the only V8 offered in 1980 and 1981. Basically a sleeved-down 302, it produced 119 hp, the lowest power ever for a Mustang V8. The 255 was mated only with the three-speed automatic transmission.
Engine Basics
Year | 1980 |
bbl | 2 barrel |
Cylinders | 8 |
Power (hp) | 119 hp |
Torque (lb/ft) | 194 ft-lbs |
Compression | 8.8:1 |
Displacement | 255 cu / 4.2 liters |
Bore x Stroke | 3.680 x 3.126 |
Engine Specs (255 cid V8)
- Cylinders front to rear: 5-6-7-8
- Cylinders front to rear: 1-2-3-4
- Firing order for most v8 engines except for 302 HO & some 351’s
- Valve arrangement: R. Side I E I E I E I E Front to rear
- Valve arrangement: L. Side E I E I E I E I Front to rear
Cylinder compression pressure | 101 PSI minimum |
Oil pressure | 40-65 @ 2000 rpm |
Spark plugs | ASF42C set to 0.050 |
Cylinder head warp limit | 0.003 in 6″ or 0.06 overall |
Thermostat starts to open / full open up to 1988 | 188-195 / 221 degrees |
Radiator cap pressure | 16 |
Timing | 10 BTDC with spout disconnected |
Valve stem to rocker arm clearance non-HO | 0.096-0.014 |
Valve stem to rocker arm clearance – HO | 0.123-0.146 |
Valve stem to rocker arm clearance non-HO allowable | 0.071-0.171 |
Valve stem to rocker arm clearance – HO allowable | 0.098-0.198 |
Timing chain deflection | .5 “ |
Manifold Vacuum | 18 inches at idle |
Distributor Rotation Counter Clockwise | Counter Clockwise |
Engine Torque Specifications
All torque specifications provided in this table are those recommended by FORD. If you use special bolts, follow the torque specifications provided by the manufacturer. I recommend that you use the 3 step torque technique where you torque down the bolts in three equal steps. Once you have reached the maximum recommended torque setting, go around one more time. Do not torque in a circular pattern. Always torque cross to cross.
Cylinder head bolts except 1993 flanged | 55-65, then 65-72 |
Cylinder head bolts 1993 flanged bolts | 25-35,45-55, then an additional 1/4 turn |
Upper Intake manifold bolts | 12-18 |
Intake manifold to block bolts | 23-25 |
Oil filter to insert engine block | 20-30 |
Exhaust manifold bolts non- 1993 Cobra | 18-24 |
Exhaust manifold bolts 1993 Cobra | 26-32 |
Valve covers | 10-13 |
Flywheel/drive plate bolts | 75-85 |
Rocker arm fulcrum bolts | 18-25 |
Oil pan to engine block bolts 1979 small bolts | 7-9, then10-12 |
Oil pan to engine block bolts 1979 large bolts | 11-13, then 15-17 |
Oil pan to engine block bolts 1980-1987 | 9-11 |
Oil pan to engine block bolts 1988 & up | 6-9 |
Oil pick-up tube to main bearing cap nut | 22-32 |
oil pump mounting bolts | 22-32 |
Crankshaft sprocket bolt | 40-45 |
Crankshaft pulley crank bolt | 70-90 |
Camshaft retaining plate bolt | 9-12 |
Main bearing cap b olts | 60-70 |
Connecting rod cap nuts | 19-24 |
Timing chain cover bolts | 12-18 |
Water pump bolts | 12-18 |
Thermostat housing bolts to 1987 | 9-12 |
Thermostat housing bolts 1988 & up | 12-18 |
fan pulley to hub bolts up to 1989 | 12-18 |
fan clutch to water pump 1990 & up | 15-22 |
Shift lever attaching bolts | 17-25 |
Auto transmission pan bolts C4 & C5 | 12-16 |
Auto transmission pan bolts A4LD | 8-10 |
Auto transmission pan bolts AOD | 6-10 |
Engine mount to block bolts | 85 |
Engine mount to frame nuts & bolts | |
Carb to intake 2150 2V | 14-16 |
Water pump to block | 12-18 |
Oil pan drain plug | 12-16 |
Pedal support brake bracket | 13-25 |
Spark plugs 1979 – 1987 | 10-15 |
Fuel pump to block | 19-27 |
Wheel lug nuts | 80-105 |
Front hub nut | 17-25, back off nut, re-torque to 10-15 |
Bellhousing to engine bolts | 28-38 |
Pressure plate to flywheel | 12-24 |
Driveshaft flange | 70-95 |
clutch self adjuster nut | 17-26 |
Fan pulley to hub | 12-18 |
Fan clutch to water pump | 15-23 |
Valve Specifications
Minimum valve margin width | 1/32 |
Intake & exhaust valve seat angle | 45 degrees |
Intake & exhaust valve face angle | 44 degrees |
Intake & exhaust valve seat width | 0.060-0.080 |
Intake & exhaust valve face runout limit | 0.002 |
Intake & exhaust valve seat run-out limit | 0.002 |
Intake stem diameter Standard | 0.3416-0.3423 |
Intake stem diameter – 0.015 oversized | 0.3566-0.3573 |
Intake stem diameter – 0.030 oversized | 0.3716-0.3723 |
valve stem to guide clearance – standard | 0.0010-0.0027 |
valve stem to guide clearance svc. limit | 0.005″ |
Exhaust stem diameter – standard | 0.3411-0.3418 |
Exhaust stem diameter – 0.015 oversized | 0.3561-0.3568 |
Exhaust stem diameter – 0.030 oversized | 0.3711-0.3718 |
Exhaust valve stem to guide clearance std | 0.0015-0.0032 |
Exhaust valve stem to guide clearance-limit | 0.0055 |
Valve spring pressure – intake 1979, 1980 valve open | 190 to 212 @ 1.36″ |
Valve spring pressure – intake 1979, 1980 valve closed | 74 to 82 @ 1.78″ |
Valve spring pressure – intake 1981, 1982 valve open | 196 to 214 @1.36 |
Valve spring pressure – intake 1981, 1982 valve closed | 74 to 82 @ 1.78″ |
Valve spring pressure – exhaust 1979 -1981 valve open | 190 to 210 @ 1.20 “ |
Valve spring pressure – exhaust 1979 -1981 valve closed | 76 to 84 @ 1.60″ |
Valve spring pressure service limit | 10 % loss |
out of square limit | 5/64 |
Installed height intake 1979 – 1987 non HO | 1 43/64 -1 45/64 |
Installed height exhaust 1979 – 1987 | 1 37/64 – 1 39/64 |
Valve lifter diameter standard | 0.874-0.8745 |
Lifter bore clearance | 0.0007-0.0027 |
lifter bore clearance service limit | 0.005 |
Crankshaft Specs
Connecting rod journal diameter | 2.1228-2.1236 |
Connecting rod journal out-of-round / taper limit | 0.005″ |
Connecting rod Bearing oil clearance desired | 0.0008-0.0015 |
Connecting rod Bearing oil clearance allowed | 0.0008-0.0024 |
Connecting rod side clearance std. | 0.010-0.020 |
Connecting rod side clearance allowed | 0.023 |
Main Bearing journal diameter | 2.2490-2.2482 |
Main Bearing journal out_of_round limit | 0.0006 |
Main Bearing journal taper limit | 0.0004 per inch |
Main Bearing journal runout – Standard | 0.002 |
Main Bearing journal runout – limit | 0.005 |
Main bearing oil clearance 1979-1981 #1 journal | 0.0001-0.0015 |
Main bearing oil clearance 1979-1981 #all other journals | 0.0004-0.0015 |
Main bearing oil clearance 1979-1981 #1 journal, allowable | 0.0001-0.0017 |
Main bearing oil clearance 1979-1981 #all other journals, allowable | 0.0004-0.0021 |
Crankshaft endplay – Standard | 0.004-0.008 |
Crankshaft endplay service limit | 0.012 |
Cylinder bore diameter | 3.680-3.6845 |
Cylinder bore out-of-round limit | 0.005 |
Cylinder bore taper limit | 0.01 |
Piston to bore clearance limit, 1979-1987 | 0.0018-0.0026 |
Piston ring side clearance, compression rings -Standard | 0.002-0.004 |
Piston ring side clearance service limit | 0.006 |
Piston ring side clearance oil ring | Snug fit |