1970 Mustang Engine Information – 428 cubic inch V-8 (7.0 L Boss V8)
429 Boss V8
The Boss 429 engine was offered late in 1969 and was rated at over 370 horsepower. It had aluminum heads with extremely large free flowing ports, contoured exhaust manifolds, a high rise intake manifold to help it gain horses.
The block was a strengthened 429 cast block. They had HP429 cast into the front left side of the block. The 4 bold main engine had forged crank and connecting rods. The first 279 (model (820-S) engines used NASCAR type connecting rods, the remainder of the engines (model 82-T) used beefed up production type rods.
The aluminum heads used oversized valves set at an angle to each other placing the exhaust valves closer to the exhaust manifold and the intake valves directly in line with the intake manifold thus the breath- ability of the engine was maximized. This “crescent” design was similar to the hemi design used in other engines. There were no head gaskets use when assembling the 429. “O” rings were used to seal all water and oil passages as well as the individual cylinders.
An aluminum intake manifold was mated with a 735 cfm Holley carburetor. Valve covers were either magnesium or aluminum depending on date of production.
429 cu / 7.0 liters
375 hp @ 5,200 RPM
450 lb/ft @ 3,400 RPM
Bore x Stroke
4.360 x 3.590
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.