If you wanted a big block engine in 1968 you could choose a 427, 428 or the new 429. The top performance motor was the 427. The 428 was a ten year old FE design, more tamed down. And the new 429 was a brand new design called the "385" series. Available in two versions in 1968, the 429 and the huger 460. The later motor was for Lincolns and Mercury's.
The 429 was unique in many ways. It offered:
- Thin wall casting
- Longer bore centers than the FE block
- Huge bearings
- Canted-valve cylinder heads forming a slightly hemi-spherical combustion chamber
- Rocker shafts were replaced with rockers riding on fulcrums with separate pedestals
The canted-valve design angled the valves in the head. This allowed for larger ports and valves. It also permitted an better unshrouded mixture of gasoline and air into the chamber.
Ford needed a better NASCAR and NHRA motor. The 427 was gone. So Ford engineers developed a unique set of heads and placed them on a 429 Mustang in 1969. This Mustang was called the Boss 429. The head design was also used on a special 302 Mustang. That car was named the Boss 302. Ford sold enough Boss 429 Mustangs to qualify the motor for racing. The aluminum heads used in the Boss 429 engines featured:
- Modified hemi-spherical design
- One long and one short rocker arm per cylinder
- A single camshaft
- Stronger main bearings
- Different oiling system
- Four bolt mains
The Boss 429 was a "385" motor but with the above changes is not interchangeable with other 429 blocks.
In 1970 the 428 Cobra Jet Motor was replaced with a 429 CJ engine. The change occurred in the middle of the production year so some early Cobra Jet cars had 428's, later cars were 429's. The 429 Cobra Jet package included:
- Bigger heads with larger ports and valves
- Stamped steel rocker arms
- Screw-in rocker studs in the early 70 models
- Guide plates like used in the Boss 302's
- Compression was increased from 10.5:1 to 11.3:1
- Cast iron intake manifold
- Single 700 cfm Rochester carb
- Rated at 370 horse power
In 1971, Ford offered the Super Cobra Jet 429. This upgrade offered:
- Four bolt mains
- Forged aluminum pistons
- Bigger oil pump
- External oil cooler
- Cast iron crank shaft with higher nodularity than the base 429
- Mechanical camshaft with adjustable rocker arms
- Single 780 cfm Holley carb
The 429 motor was phased out in 1973. It's sister motor, the 460, continued in production.
The 460 motor is a 429 with longer stroke, same bore. In 1968, when it was first offered, the 460 was rated at 360 horse power with 10.5:1 compression. By 1972 the compression dropped to 8.5:1 with a horse power rating decrease to 212 HP. The next year, 1973, saw the compression down to 8.0:1 and horse power at 200 HP. However the way horse power was stated changed during this time. Early motors were rated using flywheel or brake horsepower, in '72 net horsepower was used. (The difference being whether all the power robbing accessories are considered.)