Reply to "393 Stroker"

If your heads are D0AE (1970) castings, they have nominal 63 cc combustion chambers, and your motor has 10.0:1 compression ratio.

If your heads are D1AE (1971) castings, they have nominal 66 cc combustion chambers, and your motor has 9.7:1 compression ratio.

If you have the stock cam, it is a very mild one, less lift and duration than the cam used on the 1972 through 1974 motors (the Cobra Jets). Your engine is referred to as an "M" code engine. The 1972 - 1974 engine is known as a "Q" code engine.

The change in camshafts was made to increase the performance of the motor, not because of the lowering of the compression ratio. In 1972 the 351C 4V became the premium performance motor for the Ford line-up, so they spruced up the perfomance of the motor, making it closer in performance to the 1971 Boss 351. Besides a hotter cam, the 1972 motor also received a dual point distributor and larger carburetor. Those 3 changes combined to give the 351C Cobra Jet version much more high rpm potential compared to the earlier 1970 - 1971 351C 4V "M code" motor. The Q code motor also received a larger harmonic balancer and 4 bolt main bearing caps.

An interesting thing about the Ford engine manuals of that era, they are 1 year behind. Your 1973 manual covers the motors that were installed in 1972 cars.

cowboy from hell