Cleveland Rocks Again: Trick Flow’s New PowerPort Cleveland Heads for Ford 351C

Slide Show

Produced from 1970 to 1974, the Ford 351 Cleveland has earned a reputation as the Blue Oval’s “bad boy” V8. Need proof? Talk to a Ford guy about Clevelands and watch the reaction when you mention 4V, Boss, or R-code. We guarantee drool will be involved.

History Lesson
Ford designed the 351C as a “mid-block” engine option for passenger cars. It made more power than the 289-302-351 Windsor small blocks (and used the same engine mount locations and bellhousing pattern), and was lighter and more compact than the FE and 429/460 big blocks. The Cleveland’s cylinder heads have a canted valve arrangement similar to the big block Chevy. This allows the use of larger valves and ports to increase airflow and power production from a relatively small cubic inch envelope.

Ford made two types of Cleveland engines with designations based on carburetor type. The 2V had a two-barrel carburetor and made gobs of low and midrange torque. The 2V cylinder heads featured open style combustion chambers, 2.04 inch intake/1.77 inch exhaust valves (larger than the ones used on the 390 and 428FE big blocks), and round intake and exhaust ports. Over 90% of 351Cs were 2V engines.

The 4V Cleveland was a whole ‘nuther animal. Designed for top end horsepower, the engine came with a four-barrel carburetor. The cylinder heads had massive 2 1/2 x 1 3/4 inch intake ports that you could just about get your whole hand into. The valves for 4V engines built through 1972 were equally ginormous at 2.19 inches (intake) and 1.71 inches (exhaust). The only other Ford engine with valves that large was the 460 Police Interceptor.

There were four versions of the 4V:
• M-Code (1970-71): 62.8cc closed combustion chambers, 11:1 compression (1970), 10.71 compression (1971), hydraulic cam
• R-Code (1971 Boss, 1972 HO): 64-67cc closed chambers/11.7:1 compression (Boss), 74-77cc open chambers/9.0:1 compression (HO), solid cam
• Q-Code (1971-74 Cobra Jet):  74-77cc open chambers/9.0:1 compression, hydraulic cam

Trick Flow Solves the Cleveland Dilemma
As you can see, the Cleveland poses a bit of a dilemma. The 2V engines lack the upper rpm horsepower capabilities of their 4V cousins; in turn, the 4V engines have lousy street manners and don’t really come alive until they reach 3,500 rpm and above.

The source of the dilemma is in the cylinder heads. You’d think Ford would have made a head that combines the best qualities of the 2V and 4V designs, and you would be right—but only for Australian-market 302s and 351s, which were produced until 1982. The Aussie heads combined 2V-sized runners and valves with 4V-type closed combustion chambers, resulting in an excellent performance street head.

Factory Australian heads are sought after here in the US to upgrade 351 Clevelands (they add about one point of compression over open chamber 4V heads) or build power in 351M and 400 engines. Cleveland heads can also be adapted to readily available (and affordable) 351 Windsor blocks. This combo is commonly known as a “Clevor”.

Thanks to Trick Flow Specialties, you don’t have to hunt down a pair of Australian heads or make do with factory 4V castings. The company’s PowerPort® Cleveland aluminum cylinder heads will provide all of the airflow you’ll need to build a serious street or bracket racing engine, ready to bolt on right out of the box.

Inside the PowerPort Cleveland
Like the Aussie heads, the PowerPort Cleveland heads combine 2V-based intake and exhaust runners with 4V-style combustion chambers. However, Trick Flow engineers raised the exhaust runners .100 of an inch from the stock location. This improves the short side radius of the runners, dramatically increasing airflow. Trick Flow also modified the oil return system to improve oil drainback into the pan, and included coolant passage provisions for mating the PowerPort heads to a 351 Windsor block. A little machine work is all that’s needed to finish the conversion.

The PowerPort head is available in two versions:
PowerPort Cleveland 190 heads have 190cc intake and 112cc exhaust runners made using Trick Flow’s Fast as Cast® casting process. In English, Trick Flow digitizes CNC-ported runner profiles and incorporates them into the head casting mold design. The result is a cast head with runners that flow at near-CNC ported levels without the expense of actually CNC-machining the part…and an affordable way for you to build horsepower.

PowerPort Cleveland 190 heads also feature 62cc CNC-profiled combustion chambers with 2.08 inch intake and 1.60 inch exhaust valves. The heads comes fully assembled with your choice of 1.460 inch or 1.530 inch dual valve springs, ductile iron valve seats, valve retainers and locks, and 7/16 inch ARP rocker arm studs.

Your other choice is the PowerPort Cleveland 225 heads. These are fully CNC-ported and profiled for maximum airflow; they feature 225cc intake/115cc exhaust runners and 60cc combustion chambers with 2.08 inch intake/1.60 inch exhaust valves. The PowerPort Cleveland 225s comes fully assembled with the same goodies as the 190 heads, including a choice of 1.460 inch or 1.530 inch dual valve springs.

Trick Flow Builds a Cleveland
Thrashing engines on the dyno is fun, and an important part of Trick Flow’s development process—no cylinder head goes out the door until it’s been put through the Superflow wringer and comes out making horsepower. Trick Flow built a 383 cubic inch, 9.65:1 compression 351C to test the PowerPort Cleveland 190 cylinder heads. Engine builder Ron Greczanik stuffed the 4V block with a Probe forged crank and pistons, Eagle Specialties rods, and a Crane .236/.240 inch lift hydraulic roller cam. Other bits and bobs  include an Edelbrock Performer Air-Gap intake manifold, Trick Flow 1.73 ratio roller rocker arms, and an MSD Billet distributor.

Outfitted with a Holley 750 cfm double pumper carburetor and 1 3/4 inch dyno headers, the 351 proved to be a stout motor, cranking out almost 524 horsepower and 480 foot-pounds of torque. Like a Cleveland 4V, peak horsepower came in at a lofty 6,500 rpm; peak torque arrived at a touch over 4,500 rpm. But the PowerPort heads shine down low too, with over 400 foot-pounds of torque available at 3,000 rpm. That, friends, is power you can really use.

Thanks to Trick Flow and its PowerPort Cleveland heads, you can build a 351C (or a 351M, 400, or 351W) that is a true all-around performance engine, at home on the street or at the track. Click on the slide show and see how to make a Cleveland really rock.

Other Components
Crankshaft: Probe #10012 (forged 4340 steel, 3.750” stroke, internal balance)
Pistons: Probe SRS Series #14213-030 (forged, 16cc reverse dome)
Piston Ring Set: Probe #315-0036-030
Web Site: www.probeindustries.com