Side by side, 351C high- and low-compression chambers are easy to spot. On the left is the open 73-77cc chamber (low compression). On the right is the 61-67cc wedge chamber (high compression). The most basic choice facing 351C builders is chamber and port size. Strictly street engines may opt for open chambers and small 2V ports for good low-end torque. Street/strip engines may go with open or closed chambers depending on the compression desired. Large ports may impress people, but they do their best work at high rpm. They offer limited torque on the street unless you plan on leaving the light at 7,500 rpm.
The 351 Cleveland has never been easy to build because the best parts are elusive. Because Ford produced this engine for just four short years, it has become harder and harder to find parts in recent years. What's more, Cleveland castings have long been plagued with failure issues (cracking). Some can be repaired, but a lot of them cannot.
We can dream of Aussie heads, which are expensive and hard to find. And we may also consider aftermarket aluminum heads for the Cleveland, but those don't come cheaply, either. So, lets go with what you can expect to find at a swap meet or in the classifieds for your 351C build. Our good friend John Douglas in Riverview, Florida, builds a lot of 351C engines annually. He knows how to build a streetable 351C that you can live with daily and make lots of power with on a Saturday night.
The 351C block offers unprecedented strength in two- and four-bolt main versions. Through many 351C buildups, we have learned that all versions of this block are virtually the same except for two- or four-bolt main caps. All two-bolt main blocks can be drilled and tapped for four-bolt main caps. Strength comes from heavy main webs wrapped around 2.749-inch main bearing journals. Ironically, the 351C has a smaller main bearing journal than the 351W, which is larger at 3.000 inches. Smaller mains yield less friction, which is likely the motivation behind the smaller main bearing size on the 351C.
Cleveland oiling systems from the factory fall short in terms of oil delivery to the main bearings, which bites a lot of us who build Clevelands. It's a good idea to begin Cleveland oiling system mods at the pump. Opt for a Speed-Pro high-volume pump, which yields 25 percent more volume thanks to a wider G-rotor package and cavity. It is also advisable to install a 100-psi pressure-relief spring if you're going racing. Ideally, you will blueprint your 351C oil pump before installation. MCE Engines in Los Angeles, California, can blueprint a Cleveland oil pump for you and ship it ready-to-install. The next oiling system mod is a restrictor kit from Moroso (PN 2205), which improves oil flow to the main bearings.
The good news with Cleveland engines is that they're hardy blocks that need a little help if you intend to go racing. For street use, they need minor modification. As we have learned from other engine builds, oil passages need to be worked smooth to reduce oil turbulence. The same is true for oil drainback holes, which need help to improve oil scavenging.
We suggest having any Cleveland block checked for cracks and thin cylinder walls before proceeding with machine work. Sonic checking cylinder walls helps find weaknesses before machine work. Magnafluxing the block and crank is also necessary prior to getting started. Work out stress risers and other rough spots to prevent weaknesses and failure. You can use a die grinder on any block to eliminate weaknesses. The objective here is to reduce or eliminate any chance of failure. Coating inside surfaces with GE's Glyptol, available from The Eastwood Company, improves oil-return flow and keeps stray iron particles where they belong.
This is the 73-77cc open chamber (low compression) found on all 2V heads, all 1972-74 4V heads, and the High Output head. Although this chamber is larger, with reduced compression, it is not a desirable one. By design, it aggravates detonation by creating opposing flame fronts under hard acceleration-hence the pinging. This is the chamber to avoid if at all possible. You are limited to 4V heads with huge ports if you want wedge chambers. The Australians got it right by combining conservative two-barrel ports with smaller wedge chambers.
Cleveland Vs. Windsor-What's In A Name?
How did 351ci engines get their names? When Ford came out with a second 351ci V-8 in 1970, Ford dealer technicians found themselves faced with a lot of confusion when it came to engine identification. It is virtually impossible to confuse the 351W with a 351C because they have completely different cylinder head and block architecture. In 1970, both were still so new that Ford needed to explain the differences and give each engine a family name. Ford's solution was to name each engine for the plant from which it was produced.
Raised-deck 351ci engines were named "Windsor" for their Canadian plant across the river from Detroit. Poly-angle-valve 351ci engines with wide valve covers were named "Cleveland" for their northeast Ohio roots.
These names stuck and have been used ever since. Some confusion abounds with Cleveland and Windsor because 221/255/260/289/302ci engines were also produced at the Cleveland Engine Plant. Their castings were produced at the Cleveland foundry. Added confusion abounds when we find 289/302 heads produced at the Windsor foundry. The rule of thumb is 221/255/260/289/302ci engines were Cleveland based, with all of them produced in Cleveland. The 351W engine was Windsor produced. By the same token, the 351C was Cleveland produced exclusively.
Whenever we call 221/260/289/302ci engines Windsor small-blocks, we're mistaken. None were ever produced in Windsor. Only the 351W was produced in Windsor, Ontario-along with a smattering of 289/302 small-block heads.
Here's the more desirable 61-67cc wedge chamber (high compression) used with the 4V and Boss 351 head casting. The Aussie head uses this chamber with smaller 2V ports for best results. | 
All Cleveland foundry castings have this logo. Because all 351C, 351M, and 400M castings were produced in Cleveland, you won't see a "WF" logo (Windsor Foundry). | 
Clevelands and Midlands have different cooling passages between the block and heads from what we find with 289/302/351W engines. Because the 351C, 351M, and 400M have dry intake manifolds, coolant flows across the engine via cooling passages like this one between the heads and block. When we bolt Cleveland heads on a Windsor block, this passage is eliminated, with a new cooling passage drilled to accommodate 289/302/351W intake manifolds. |
Externally, 351C-4V heads are identified by this "4" in each corner. | 
Screw-in adjustable rocker stud pedestals look like this. This is also what you can expect to see with Boss 351 and High Output heads with adjustable rockers and mechanical tappet camshafts. | 
Hydraulic lifter 351C engines have this bolt/fulcrum rocker-arm fulcrum designed for a no-adjust rocker arm. Small-block Fords (302 and 351W) from 1977-up have the bolt/fulcrum, no-adjust rocker arm. |
John Douglas' porting regiment includes taking stress risers and bumps out of chambers and ports. Stress risers in combustion chambers create hot spots that can cause detonation problems. This is especially important in open chambers notorious for detonation issues. John works the bowls and valve seats to smooth airflow. It looks like John has gone with a standard three-angle valve job here for the street. A five-angle valve job costs more, but it produces even more airflow. | 
John specifies Fel-Pro in his engine builds. We recommend Fel-Pro Print-O-Seal head and intake manifold gaskets for exceptional sealing. This isn't a biased opinion based on advertising dollars-it's based on years of experience with Fel-Pro gaskets and dozens of different engine builders who insist on them. | 
Cylinder head installation and torque values may not seem like a big deal, but they are. We've even had builders suggest no sealer on cylinder-head gaskets and even cleaning the factory clearcoat off head-gasket fire rings with carburetor or lacquer thinner. This allows for better heat dissipation and cylinder sealing because high revs actually lift cylinder heads off the block. Having a clean, undisturbed fire ring is critical during installation. Use Latex gloves to keep skin oil off your gaskets. Proper head gasket installation is confirmed by looking for the gasket in the lower left hand corner of this image. If they're installed properly, you will see the gasket. |