351C Performance With Common Parts - A Cleveland Course of Action

Heads are torqued inboard to outboard in one-third values. Total torque for 351C heads is 110 ft-lb. Divide that into thirds, or 37 ft-lb of torque per sequence.

Crane has provided John with a 52HR00026 hydraulic roller camshaft. This is an aggressive 52-HR-232/352-2S-10 roller cam with 110-degree lobe separation, 0.609/0.621-inch valve lift, and 294/298 degrees duration. This yields a civilized idle and comes on strong at high revs.

Heads
Cleveland heads were produced in several variations. Most common is the two-barrel (2V) casting with 74-77cc open chambers, 2.050-inch intake, and 1.659-inch exhaust valves. These are easily identified by their open "bowl" chambers and D0AE-E or DOAE-J casting numbers. This is a good street head because the port size is more conducive to the low- to midrange torque we want on the street. Aftermarket intake manifold availability is better with these heads as well. The 2V head was used not only on the '70-'74 351C, but the 351M and 400M engines as well, which explains availability.

Four basic types of 351C-4V heads were produced-closed chamber, open chamber, Boss 351, and High Output. Much of it has to do with compression ratio and mechanical lifter use.

Early 351C-4V engines were fitted with closed-chamber (61-64cc), large-port heads. This is an excellent high-revving street/strip head for those who want iron heads. In 1973-'74, Ford went with a 73-78cc open chamber in the 4V head, virtually identical to the 2V head. This head is easily identified by its large ports and 2V-style open chambers. It's the least desirable head available, but sometimes it's all you're going to find.

The '71 Boss 351 head is extremely hard to find, thanks to adjustable stud-mounted rocker arms and closed 64-67cc wedge chambers. The '72 High Output that came a year later has adjustable stud-mounted rockers like the Boss 351. But larger 73-76cc open chambers make it less desirable than the Boss 351 head. The truth is, aside from the stud-mounted rocker arms and large ports, the '72 High Output head isn't desirable outside of a restoration.

These are Crane Energizer 1.7:1 forged aluminum rocker arms designed for the 351C, 351M, and 400M. They sport a precision needle bearing fulcrum and roller tip to reduce friction. John stresses checking rocker arm-to-valve stem geometry, which is rooted in pushrod length. When it comes to adjustment, have both valves at rest on compression stroke, and then slowly tighten the poly-lock until the pushrod cannot be turned. Then tighten 1/2-3/4 turn for street.

John suggests plenty of assembly lube on pushrod tips, roller tappets, and rocker arms. These are Crane hydraulic roller tappets (PN 36432-16) for the 351C that are linked together instead of retained with a spider and dog bones. Although this is more expensive, it's a better system that requires no block retrofit work. John suggests soaking these guys in engine oil overnight for complete lubrication saturation.

We cannot stress enough the importance of oil-pump clearances. Oil pumps do not always clear crankshaft counterweights, and sometimes the pump housing must be ground to clear the crank. Check all clearances and make your minimum 0.060 inch.

351C Performance Pointers John suggests always checking oil pick-up dimensions before anchoring the pan. An oil pick-up pressed against the pan sump can chafe and create metal shavings for the oil pump to ingest.

351C Performance Pointers Cleveland engines need serious cooling capacity-the help you get from a high-flow water pump. We suggest cleaning rough surfaces that can create fluid turbulence and hot spots.

351C Performance Pointers All 351C, 351M, and 400M engines have this coolant flow restrictor just below the thermostat as shown. Do not remove this restrictor.

Oil-pan installations seem like such a simple task, but if you want to prevent leaks, pay close attention to what you are doing. John likes 3M's yellow Gasket Adhesive, and uses it sparingly on the rails only. At the end gaskets, he uses The Right Stuff; a silicone adhesive in a pump can-again, sparingly. Pan bolts are snugged, but not over-torqued. Overtorque these and you distort the pan. It doesn't take much torque to snug the gaskets adequately.

John uses a thin film of The Right Stuff at the intake ports to reduce chances of an internal vacuum leak. Along the block rails, he rolls down a bead of RTV or The Right Stuff. You don't need much here. As it cures, it expands.

John has chosen Holley's 4150 750-cfm carburetor atop a Weiand X-celerator single-plane manifold. As you were taught in Engine Basics 101, a single-plane manifold makes all kinds of high-end horsepower, but it is not an all-around street manifold. John also chose a Plenum Divider Kit (PN 128351) for this manifold. Torque isn't stellar under 4,000 rpm, but above 4,000, get out of the way-374.7 lb-ft at 5,300 rpm, with 408.8 hp at 5,900 rpm. Not a broad powerband, but plenty at full throttle above four grand on the dyno.