It has been reported that the intake manifold on the 351-C Ford engine is critical as far as torque rate and sequence are concerned.

Intake leaks, although very slight, will affect engine performance. Caution engine assembly mechanics to apply the manifold with care and adhere to the following instructions in three steps:

1. Torque all bolts in sequence to 8-10 ft. lbs.

2. Torque all bolts in sequence to 15-20 ft. lbs.

3. Torque all bolts in sequence to specifications:

5/16" bolts should be torqued to 23-25 ft. lbs.

3/8" bolts should be torqued to 28-32 ft. lbs.

Installing mechanics should be advised that the manifold requires retorquing in sequence to full torque after the engine has reached normal operating temperature. (See illustration)

(P53)