Tech | Custom Engine Build
Over in the Ford camp, they watched with great interest as the new 396 Daytona Mystery Motor from Chevrolet was introduced in 1965. The very successful engine featured a splayed-valve arrangement, which offered improved flow potential when compared to a conventional inline valve configuration. Partly in response to this successful GM offering, Ford introduced the 335-series 351 Cleveland engine for the 1970 model year. Produced from 1970 to 1974, the Ford 351 Cleveland has earned a reputation as one of the Blue Oval's best V-8 engines. Ford designed the 351 Cleveland as a "mid-block" engine option for passenger cars. It made more power than the 289-302-351 Windsor small-blocks, but used the same engine mount locations and bell housing pattern. The Cleveland engines were lighter and more compact than the FE and 385-series (429/460) big-blocks. The Cleveland's cylinder heads offered a canted-valve arrangement similar to the big-block Chevy. This allowed the use of larger valves and ports to increase airflow and power production from a relatively small cubic-inch package.
Ford made two types of Cleveland engines with designations based on carburetor type. The 2V had a two-barrel carburetor and made lots of low and midrange torque. The 2V cylinder heads featured open-style combustion chambers with a 2.04-inch intake valve and a 1.77-inch exhaust valve. These valves were larger than the ones used on the 390 and 428 FE big-blocks. The 2V heads had round intake and exhaust ports. More than 90 percent of Cleveland production was 2V engines. The 4V Cleveland was a whole different matter.
The Power Port head is available...
The Power Port head is available in two versions: The Power Port Cleveland 190 heads have 190cc intake and 112cc exhaust runners using Trick Flow's Fast as Cast casting process. Trick Flow digitizes CNC-ported runner profiles and incorporates them into the casting mold designs for the cylinder head. The result is a cast head with runners that flow at near CNC-ported levels without the expense of actually CNC-machining the part. That makes a Fast as Cast head an affordable way to build horsepower. The Power Port Cleveland 190 head also features 62cc CNC-profiled combustion chambers with 2.08-inch intake and 1.60-inch exhaust valves. The head comes fully assembled with your choice of 1.460-inch or 1.530-inch dual valvesprings, ductile iron valve seats, valve retainers and locks, and 7/16-inch ARP rocker arm studs. Your other choice is the Power Port Cleveland 225 head. This head is fully CNC-ported and profiled for maximum airflow.
The 4V Cleveland heads were designed for top-end horsepower and the engine came with a four-barrel carburetor. The cylinder heads had massive 21/2-x13/4-inch intake ports and the valves for the 4V engines, which were built through 1972, were equally generous with a 2.19-inch diameter on the intake and 1.71 inches for exhaust. The only other Ford engine with valves that large was the 460 Police Interceptor.
There were several versions of the Cleveland 4V. First was the M-code, produced in 1970-1971. It had 62.8cc closed combustion chambers and an 11:1 compression ratio. For 1971, compression was reduced to 10.7:1. Next was the R-code, produced in the 1971 Boss 351. It had 64-67cc closed chambers and a compression ratio of 11.7:1. By 1974, the Boss 351 had 74-77cc open chambers and a 9.0:1 compression ratio. The Q-Code version found in 1971-1974 cars had 74-77cc open chambers and a 9.0:1 compression ratio.
Trick Flow's 351 Cleveland...
Trick Flow's 351 Cleveland started with a 1971 4V block, bored 0.030-inch over, line-honed, and decked. Here, resident engine builder Ron Greczanik holds an Eagle Specialties/Probe Industries connecting rod and piston assembly. Creating a 383 stroker Cleveland requires 6.125-inch rods. The Eagle ESP H-beam rods are forged from 4340 steel and are rated up to 700 hp and 7,500 rpm. The Probe forged piston is designed specifically for 383ci and 408ci Cleveland strokers. It features full-floating wristpins and a 16cc reverse dome to help keep compression in check with the small 62cc combustion chambers. The ring pack is also from Probe; it features 1/16-inch top and secondary rings and a 3mm oil ring.
As you can see, the Cleveland engines pose a bit of a dilemma. The 2V engines lack the upper rpm horsepower capabilities of their 4V cousins and in turn the 4V engines had lousy street manners and didn't really come alive until 3,500 rpm and above. The source of the dilemma was 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 U.S. to upgrade the 351 Cleveland because they add about one point of compression over open chamber 4V heads. Cleveland heads can also be adapted to the readily available and more affordable 351 Windsor blocks. This combo is commonly known as a "Clevor."
Now, 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 Power Port Cleveland aluminum cylinder heads will provide all the airflow you'll need to build a serious street or bracket racing engine and they're ready to bolt-on right out of the box. The Trick Flow Power Port Cleveland heads are similar to the Ford Aussie heads in that the Power Port Cleveland units combine 2V-based intake and exhaust runners with 4V-style closed combustion chambers. However, Trick Flow engineers raised the exhaust runners 0.100-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 drain back into the pan, and included coolant passage provisions for mating the Power Port heads to a 351 Windsor block. A little machine work is all that's needed to finish the conversion.
The ARP rod bolts are torqued...
The ARP rod bolts are torqued to 63 ft-lb in three steps. The crankshaft is a 4340 forging from Probe. The internally balanced crank has a 3.750-inch stroke and 2.100-inch rod journals (same as small-block Chevy). Note the four-bolt main caps. These were factory on R-code 4V engines, but all Cleveland blocks and caps can be drilled for a four-bolt conversion.
The camshaft is a Crane PowerMax...
The camshaft is a Crane PowerMax retrofit hydraulic roller. Duration at 0.050 is 236 degrees intake/240 degrees exhaust; valve lift is 0.621/0.631-inch with the factory rocker arm ratio. The cam is designed to make power from 3,500 to 7,000 rpm, right in the meat of a hot Cleveland's powerband. With Crane Cams undergoing reorganization, the PowerMax cam is not currently available. A close alternative is a Comp Cams Magnum roller grind with 244 degrees duration at 0.050 and 0.612-inch valve lift; the powerband is a little lower at 2,500 to 6,000 rpm.
Cleveland engines use this...
Cleveland engines use this two-bolt thrust plate to keep the camshaft in place. Thrust plates with Torrington bearings are available from Summit Racing and Comp Cams, and can free up some power by reducing friction. The two plugs are for the main oil galleries. The Cleveland oiling system gives priority to the cam bearings at the expense of the rod and main bearings, which gave the Cleveland a reputation as a "bearing spinner" at high rpm.
After installing the timing...
After installing the timing chain set, Ron degrees the camshaft. It ended up at 108 degrees.
Cleveland engines have the...
Cleveland engines have the thermostat in the front of the block, unlike the 351 Windsor, which has the thermostat in the manifold. Coolant exits the heads, goes through the block, and out to the radiator so the intake manifold stays "dry". This steel plate acts as a timing chain cover; the factory water pump bolts directly to it. These plates usually crack and corrode over time. Summit Racing offers a laser-cut steel replacement. Make sure to use the factory brass restrictor plate underneath the thermostat to help prevent overheating issues.
The oil pump is a Melling...
The oil pump is a Melling standard pressure and standard volume unit with a Milodon pickup. Since the Cleveland's oiling system is biased to delivering oil to the top end at the expense of the rotating assembly, a high volume or even high pressure pump is not required.