The 302 was Ford's most popular small-block engines of the late 1960s and early 1970s. Released in 1968, the 302 replaced the 289. One year later, a high-performance version of the 302 was released as optional equipment for the Mustang. This special engine was called the Boss 302. Both engines used the same block, but differences between cylinder heads do exist. Whenever rebuilding the 302's cylinder heads, knowing the specifications of the heads is essential to determining whether repairs must be made or parts must be replaced.
Valve angle includes two specifications, seat angle and face angle. Both angles are measured in degrees. Seat angle for both versions of the 302 is 45 degrees. Face angle for both versions of the 302 is 44 degrees.
Valve spring pressure for the standard 302 is 180 pounds at 1.23-inches. Spring pressure for the Boss 302 is 315 pounds at 1.31-inches. Valve spring installed height for the standard 302 is 1 21/32 of an inch and 1 13/16 of an inch for the Boss 302.
Clearance for the intake valves on the standard and Boss versions of the 302 is within a range of 0.0010 and 0.0027-inches. Clearance for the exhaust valves for the standard 302 is within a range of 0.0010 and .0027-inches and within a range of 0.0015 and 0.0032-inches for the Boss 302.
Stem diameter for both the intake and exhaust valves is the same for both versions of the 302. Intake stem diameter is 0.3420 inches. Exhaust stem diameter is 0.3415 inches.
The torque specification for each cylinder head bolt for both versions of the 302 is between 65 and 72 foot-pounds of torque.
