1970 Mustang 428 Cobra Jet V8

1970 Mustang Engine Information & Specs – 428 Cobra Jet V8 (7.0 L)

428 Cobra Jet V8 Technical Specs & Data

1970 Mustang Engine Information – 428 cubic inch V-8 (7.0 L Cobra Jet V8)

During the mid-1968 model year, a drag racer for the street could be ordered with this optional 428 cu in (7.0 L) Cobra Jet engine which was officially rated at 335 hp all of these Mustangs were issued R codes on their VINs. The 428 Cobra Jet engine used a nodular cast iron block and crankshaft, forged steel piston rods and aluminum pistons. The 428 Cobra Jet used an external oil cooler as well.

Engine Basics

Year 1970 “Q” Code (Cobra Jet)
bbl 4
Cylinders 8
Power (hp) 335 hp @ 5,400 RPM
Torque (lb/ft) 440 hp @ 3,400 RPM
Compression 10.6:1
Displacement 428 cu / 7.0 liters
Bore x Stroke 4.130 x 3.984

Year 1970 “R” Code (Cobra Jet RA)
bbl 4
Cylinders 8
Power (hp) 335 hp @ 5,400 RPM
Torque (lb/ft) 440 hp @ 3,400 RPM
Compression 10.5:1
Displacement 428 cu / 7.0 liters
Bore x Stroke 4.130 x 3.984

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.

Head bolts 80-90
Main cap bolts 95-105
Rod bolts 53-58
Intake bolts 32-35
Exhaust manifold bolts 18-24
Harmonic damper 70-90
A/C Compressor mounts
Engine fan
Motor mounts to engine
Bellhousing bolts 25
Trans to bellhousing
Flywheel to Crankshaft 75-85
Oil pan bolts 12
Valve cover bolts 10
Carburetor mount bolts
Oil pump 15
Spark plugs
Trans. inspection plate
Water pump bolts 20
Clutch pressure plate 35
Water pump
Upper cam gear 40
Rocker arms 45
Main cap cross bolts 40

Crankshaft Bearing Journal Specifications

Main Bearing Journal (inches)

Journal Diameter 2.7484 – 2.7492
Oil Clearance 0.0010 – 0.0020
Shaft end play 0.004 – 0.010
Thrust on number 3

Connecting Rod Journals

Journal Diameter 2.4380 – 2.4388
Oil Clearance 0.010 – 0.0030
Side clearance 0.010 – 0.020

Piston Ring Specifications

Comp Ring Width

Top 0.0774 – 0.0781
Bottom 0.077 – 0.078

Ring side clearance

Top 0.002 – 0.004
Bottom 0.002 – 0.004
Oil ring Snug

Ring gap width

Top 0.010 – 0.020
Bottom 0.010 – 0.020
Oil Ring 0.015 – 0.035

Piston Specifications

Code Red 4.1284 – 4.1290
Code Blue 4.1296 – 4.1302
0.003 Oversize 4.1308 – 4.1314
Piston to Cyl. Bore clearance 0.0015 – 0.0023
Piston Pin Bore Dia. 0.9752 – 0.9755

Valve Specifications

Year 1970
Seat angle Intake 30, Exhaust 45
Face angle Intake 29, Exhaust 44
Valve spring pressure lbs/inches 265 @ 1.13
Valve spring installed height (in) 1 13/16
Stem guide clearance (in) – Intake 0.0015 – 0.0032
Stem guide clearance (in) – Exhaust 0.0015 – 0.0032
Stem Diameter (in) – Intake 0.3715
Stem Diameter (in) – Exhaust 0.3710