Ford 351 Cleveland Deep Dive: Heads, Oiling, Builds

Ford builds a small block with race-bred canted valves and ports big enough to swallow a flashlight, then kills it after just a few years. If the 351 Cleveland was so good, why didn’t it keep going? Welcome back to Bono’s Garage. If you’ve ever stared down a Cleveland 4V intake port, you know it’s not your garden-variety small block. It’s a hallway: canted valves, massive cross-section, and a chamber design that was so far ahead of the gas you could buy at the pump it was crazy. So here’s the question again: if the 351 Cleveland was that good, why did it die a quiet death? Today we’ll tell the whole story, including the crazy head engineering, boiling issues, and how to build one that doesn’t suck. Then we’ll settle the Cleveland versus Windsor debate like grown-ups. By the end of this video you’ll know exactly how to spot a real 4V head, why quench is more than a buzzword, and how the Cleveland small block made big-block power through airflow and physics. From conception to early death, and from American muscle to Aussie street heroes, this is everything that made the 351 Cleveland the most misunderstood Ford small block ever built. This is your 351 Cleveland masterclass. Look back at the late ’60s and Ford was all in on racing. They’d just blown the doors off Le Mans with the 427 side-oiler in ’66. Between NASCAR and Trans Am, Ford’s engineers had learned one thing: airflow wins races. The faster you could spin it, the more power you made, but that only worked if your heads could move enough air to keep up. At the same time, the Windsor plant in Canada couldn’t keep up with small-block demand, so Ford’s engine engineers in Cleveland, Ohio were told to build their own version. The mission was simple: build a small block that could take a deep breath at high RPM, then drop it into street cars and let the image sell the hardware. Racing credibility sold cars. If the same basic engine powered Boss Mustangs and stock cars, it wouldn’t just win trophies, it would win showroom traffic. Enter the 351 Cleveland. What came out wasn’t just a copy; it was a whole new take on how a small block could breathe. It was a small block by Ford standards but used big-block thinking up top. The heads were a clean-sheet design, and on paper it looked incredible: massive ports, canted valves similar to the 429 and 460, and big valve sizes that let it breathe like an engine almost twice its size. It sat next to the Windsor on the showroom floor. The Cleveland was the hot ticket for a couple of shining years—Boss 351s, Panteras, Torinos—all running a small block that could hang with the best from GM and Mopar. It had the swagger, it had the numbers, and for a while it had the spotlight. North American production kicked off in 1970 and wound down after 1974. That is quick. In that window the lineup included the 351C 2V for street torque, the 351C 4V for high-RPM heroics, the one-year Boss 351 in ’71 that showed what the architecture could do, and later Cobra Jet variants when emissions and lower compression started kneecapping the party. The 351 Cleveland was the first member of what Ford called the 335 engine family. The name came from management’s insistence that the engine be greater than 335 cubic inches, and it stuck as the project name. The family shared a lot of design DNA: wide pan rails, canted-valve heads, and castings meant to be modular across cars and trucks. Something that could scale from a high-revving 351 for Mustangs and Torinos to a torquey 400 for full-size cars and pickups. I’ll save the M-block and 400 story for another video, but remember: the Cleveland wasn’t a one-off. It was the starting point for a whole generation of Ford V8s built around airflow, strength, and modular casting. So why did it fade so quickly? A few reasons stacked up, and if you’ve seen my other videos about engines from this era, the main chorus is the same: emissions rules turned brutal and compression came down. Those massive 4V ports needed a cam, aggressive gear ratios, and a high-flow carb to shine — things that became harder and harder to justify. Insurance companies didn’t help; they started hammering high-compression, high-horsepower cars with premium hikes so steep that buyers were paying more to insure a car than to own it. Anything with a big cam or high compression got labeled high risk, and Ford’s performance engines were in the crosshairs. Profit-wise, Ford already had tooling, supply chains, and a massive aftermarket built around the Windsor block. The Windsor plant in Ontario had been cranking out small blocks since the early ’60s; it had huge production capacity, established supply lines, and many livelihoods tied to keeping those machines running. The Cleveland plant, by contrast, was newer, smaller, and building an engine that didn’t share many components with the rest of Ford’s lineup. So when the early ’70s hit with tighter emissions, pricier fuel, and punitive insurance, it wasn’t even a close boardroom call. The Cleveland wasn’t killed because it was bad — it was killed because the world around it changed, and the Windsor fit that world better. Australia didn’t face the same tug-of-war. They had already invested heavily in Cleveland tooling for the Falcon GTs and doubled down, continuing to develop the heads and refine the chambers year after year. To be clear, Ford stopped building the 351C in the U.S. after the 1974 model year, but the Cleveland engine plant itself kept going and was retooled for newer engines — everything from small V6s to more modern units — and stayed active for decades after the Cleveland V8 was gone. While Ford in the U.S. moved on to the 351M and 400 in the Windsor family, Australia initially imported complete 351Cs from the U.S., then stockpiled about 60,000 American cast blocks when Dearborn stopped production. Once those ran low, Ford Australia started casting their own Cleveland blocks at the Gong Foundry. That’s where the 302C and the Aussie 351 came from — the same basic Cleveland design, but smaller. Ports and those closed-chamber heads everybody loves today. That tells you something important: the Cleveland wasn’t a dead end; it was a victim of timing and priorities here in the States. Normally in an engine video I would start by talking about the block, but what makes the Cleveland engine special are the heads. The Cleveland engine shipped with two different head configurations from the factory: 2V and 4V. The V doesn’t stand for valve, as you might think, but for Venturi, since they were meant to be paired with two-barrel or four-barrel carburetors. All Cleveland heads were two-valve heads. The primary difference was the breathing design. 4V heads were designed to breathe far more, with huge intake and exhaust ports. Before we get deep into ports and chambers, we need to speak the same language: two quick concepts, shrouding and quench. Shrouding is your straight-valve setup, like a Windsor or a traditional small block. When the valve opens and gets close to the cylinder wall, the air gets pinched off. That shrouding kills low- and mid-lift flow — the RPM range where street engines usually live. The canted valve arrangement is typical of Cleveland heads. The valve is tilted back and away from the wall, so as it opens it unshrouds itself. You get much more flow without needing a monster cam. Ford didn’t invent this for the Cleveland; they borrowed it from the 429 and 460 big blocks — it works there and it works here. Quench refers to a closed-chamber design. The flat pad is the quench pad. When the piston comes up, the gap between the piston and pad is really tight, about 0.035 to 0.040 inches. That squishes the mixture across the chamber, forcing the air and fuel to tumble and mix, which speeds up the burn and helps fight detonation because the charge burns fast and predictably instead of lazy and patchy. Compare that to an open chamber, where Ford basically milled out the whole section into a big bowl: no real squish or tumble and a lazier burn. That worked for emissions but not for throttle response or knock resistance. That’s why the early closed-chamber 4V heads are so desirable. In the U.S., every 2V head got the open chamber; only the early 4V heads had the good closed quench. But down in Australia, Ford kept the smaller 2V ports. Street velocity, and they also kept the closed chamber. That’s why the Aussie heads are the hot street combo today: small ports, good velocity, and real quench. Now that we have those two ideas straight, let’s talk about the ports themselves. Cleveland 4V heads were absolutely unhinged for a production small block: huge intake runners, gigantic valves, with that canted layout and almost no shrouding at the gasket. The 4V intake port window is about 2.5 by 1.75 inches — that’s the size of a Motorola power brick. That brick-sized hole is feeding 2.19-inch intake and 1.71-inch exhaust valves — that’s the bottom of a spray can and the size of a challenge coin, respectively. That’s how Ford ended up with a small block that breathes like a big block. The 2V ports pull things back to reality: a much smaller window, more like a dog tag, but still with canted valves. Still good flow, just tuned for street velocity instead of 7,000 RPM dyno pulls. You lose some top-end bragging rights, but the engine wakes up much earlier in the RPM range, which on real roads actually matters more. All factory Cleveland heads were cast iron; there were no aluminum options from Ford. The early closed-quench 4V chambers measured around 61 to 63 cc, while the later open-chamber 4V and all 2V heads were closer to 74 to 77 cc. That change alone dropped compression almost a full point. Most early 4V engines ran roughly 10.7:1 compression, while later open-chamber versions were closer to 9:1 or even the high eights depending on piston dish and how far the piston sits in the bore from the factory. Back in the early ’70s that mattered because premium meant high-octane, leaded fuel. When unleaded and lower-octane blends took over, those high-compression closed-chamber combos became picky about spark advance and fuel quality. The open chambers were Ford’s answer: cheaper to build, burned cleaner, and tolerated the lousy pump gas of the era. Those two head designs gave the Cleveland a split personality depending on your head choice — brutal on the track with a 4V and high compression, or smooth and drivable on the street with a 2V and open chambers. To tell the difference between Cleveland heads, look at the intake face: 4V ports are rectangles big enough to lose a socket in, while 2Vs are shorter and more oval. If you can inspect more closely, verify by using casting numbers on the underside of an intake runner after the intake is off; the date code is also under the valve cover. Underneath the Cleveland block itself is a stout piece of iron with surprisingly good main webbing for a small block of its era. The deck height is 9.206 inches, putting it squarely in small-block territory. The rotating assembly geometry is well balanced for RPM. With a 4-inch bore and 3.5-inch stroke, the 351C carries a 1.65:1 rod ratio thanks to its 5.780-inch connecting rods, which helps it rev cleanly as long as the rest of the combo is built to let it breathe. The main journals measure 2.75 inches, smaller than the 3-inch mains used in later 351M and 400 engines, which means less bearing speed and less drag at high RPM. Crank journals are wide and strong. Clevelands can handle 6,000-plus RPM without drama if the clearances and balances are right. A bare Cleveland block weighs about 190–210 lb, and a complete long block tips the scale near 525 to 575 lb depending on accessories and intake choice. That’s right in line with other Ford small blocks, but a little heavier than a Windsor thanks to beefier castings and heads. It uses the same firing order as the 351 Windsor. Where people really start arguing is the oiling path. You’ll hear folks say that the Cleveland feeds the top end first or that it starves the mains because of how the galleries are laid out, and that’s close to the truth but not the whole picture. The oil pump sends pressure straight up the front of the block right next to the number-one main and cam bearings, and a diagram can make it look like those bearings should get oil first. Hydraulically, though, oil takes the path of least resistance, and in a Cleveland that path is the big right-side lifter gallery. It’s a long, wide passage that feeds all eight right-side lifters and several cam bearings, so oil rushes down that gallery before it commits to dropping into the mains. Once the galleries fill and the system builds pressure, the mains then start getting their share, so the number-one bearing isn’t dry—it’s just not first in priority. At low RPM none of this is a big deal because there’s plenty of pressure to go around, but when you spin a Cleveland hard those big lifter bores and generous passages become a large leak path. The top end can dump more oil than the pump can replace, and since the mains are last in the hydraulic order they’re the ones that pay the price. That’s why serious builders talk about lifter bushings, gallery restrictors, and matching the right pump to the build. Bushings and restrictors tighten the leak paths, and a high-volume pump keeps pressure where the crank needs it. Do that, and a Cleveland will run north of 6,000 rpm all day long without losing a bearing. A fun bit of Ford trivia: the Cleveland’s oiling reputation gets compared to the old FE engines, especially the early center-oilers. Those FEs fed the crank last, which is why Ford introduced the famous side-oiler. The Cleveland isn’t the same situation, but the symptoms are similar. Why didn’t they give the Cleveland the same fix? Timing, priorities, and cost. Ford was designing a high-volume street motor that needed to meet emissions and cost targets, not a race engine. At normal street RPM that’s no problem; the issue only shows up when you spin it hard for long stretches, exactly what racers love to do, and racers then hot-rodded the valve system. One more thing to note if you’re building one: most production Clevelands run a non-adjustable valve train. That means stamped rockers on cast pedestals, the same setup Ford used on their big 429 and 460 engines. The hydraulic lifters take up the slack automatically, so there’s no lash to set with a wrench. If you need more or less preload, you change the pushrod length. Shim the fulp. The Boss 351 and later 351 HO were the exceptions. They got screw-in studs, guide plates, and solid lifters, which meant a fully adjustable setup built for real RPM. That’s one of the reasons those two are the ones everybody still talks about. The name of the game with this engine is airflow. Induction strategy is where you make or break a Cleveland. A 4V with a tiny cam and a lazy dual-plane intake can feel like a tractor that lost its wallet until about 3,000 RPM. That’s not the engine’s fault; that’s mismatched parts. The 4V’s massive, 250-ish cc intake runners move a ton of air up front, but they need velocity to work down low. Give it some cam duration, decent lift, and an intake that actually feeds those ports. Then back it up with real gear and converter, and suddenly the lazy disappears. You get exactly what Ford intended: the top-end freight train. On the 2V, you can lean toward a shorter cam, keep the dual plane, and enjoy crisp throttle and street torque. The smaller 190-to-210 cc ports build velocity fast, which means better low-end pull and clear mixture motion through the midrange. Carb sizing matters. Don’t strangle it, but don’t slap on a barn door either. A well-calibrated 650 to 750 CFM carb is perfect for most 351C street builds, while a hotter 4V combo loves 750 to 850 CFM when the RPM is there. If you go EFI, the giant-port personality of the 4V gets a little friendlier at low speed. Modern fuel control and injector timing help fill in that off-idle hole and make the Cleveland behave like a high-tech small block it always kind of wanted to be. There are a lot of terms around, so let’s narrow in on variance for a moment because the term Cleveland covered a few different animals. I’ve already gone over the head versions, but it’s worth looking again in relation to where they all ended up within the larger Cleveland line. To start with, here’s how the codes break down. The H code was the 2V street engine. The M code was the hot, closed-chamber 4V. The R code was a solid-lifter Boss. The later Q code was the tamed-down Cobra Jet with open chambers for emissions. The letters changed, but the heart of the Cleveland stayed the same. Down in Australia, things got interesting. The Aussie 302 C and 51C heads blended the best traits: two V-sized ports for velocity with closed quench chambers for detonation resistance. That combo made a lot of street builds feel stronger than the spec sheet would suggest. They’re the full caro of Cleveland swaps for a reason. You’ll find Clevelands in Mustangs, Torinos, and even the Tomaso Penta where that high-flow 4V really showed off. Across the Pacific, Australian Falcons were out there turning the same architecture into Brathurst racing legend. Here’s a list compiled from known factory data and enthusiast sources. Local options or export versions may differ. Before we move on, a quick name trap: the 351M and 400 are part of the same 335 engine family, but they’re not true Clevelands. They use a taller deck, larger mains, and a different bell-housing pattern. Some parts interchange, but if you call a 351M a Cleveland, be ready for an internet jockey to call you a noob. Let’s talk about what usually trips people up with these engines and what actually fixes it. First up: oiling and RPM. I’ve said before, the Cleveland’s oil system can starve the mains if you spin it hard with loose clearances or worn The fix depends on how wild your build is. For serious engines, lifter bore bushings keep oil where it belongs. You can also add restrictors to the lifter galleries to slow down the flow upstairs. As always, match your oil pump to the combo. A high-volume pump is great when the system is set up for it, but it’s just a band-aid if you’re masking wear or bad geometry. Cleveland cooling is different. It wants the correct Cleveland-style thermostat or a restrictor plate. There’s a bypass passage built into the housing that needs to be managed so the engine reaches temperature and circulates correctly. The proper thermostat has a little hat or sleeve that closes the bypass once it’s warm. If you’re on a Windsor-style thermostat, that bypass stays open and you’ll have weird warm-ups, hot spots in the heads, and an engine that always seems too warm no matter what you do. These blocks and heads have been around for 50 years or more. You’ll see core shift, valve guide wear, and the occasional mystery machine work from a previous rebuild. If you’re planning a major rebuild, get the block sonic checked before you spend money on parts. On the heads, check valve guides and seats carefully. Detonation on open-chamber heads is a real concern. With modern pump gas, you can’t get away with the same compression and timing those engines ran on leaded premium. Open-chamber 4V heads especially can rattle if you push them too hard. If you’re chasing power, a modern aftermarket head with a tighter heart-shaped chamber is a smart upgrade. More on that later. There are a few different ways you can build up a Cleveland depending on how wild you want to get: street, street/strip, or all-out track. Each combo changes cam specs, compression, and gearing. If you want the full recipe list — everything down to lift numbers and header sizes — I have it all laid out on bonelessg.com. The link is in the description. At the factory, Cleveland was ahead of its time. The aftermarket finally caught up. Fifty years later, the parts catalog for this thing is wild. You can build a Cleveland from bare iron to high-power setups, except maybe the block itself. Today’s aluminum Cleveland heads are basically a cheat code: you get 4V-level top-end airflow with smaller, faster ports that don’t go to sleep at 2,000 rpm. Companies like Trick Flow, CHI, and Edelbrock have the formula nailed. They feature modern heart-shaped quench-style chambers that let you run real compression on pump gas without detonation. Pair that with a dual-plane intake that matches the port cross-section you actually have, and you suddenly have a Cleveland that acts civilized in traffic and wicked at wide-open throttle. The oiling fixes are old news now, dialed in and improved: lifter bore bushings in serious builds, gallery restrictors to keep pressure where it belongs, and high-volume pumps that actually match the clearances you set up. Run a real oil pan — seven or eight quarts — with proper baffling, and use a pickup that’s welded or safety-wired so it doesn’t vibrate off and ruin your weekend. Here’s a bit of free advice: don’t oversize the exhaust just because it’s a Cleveland. Small tubes make torque. 2V heads love 1-5/8 to 1-3/4 inch headers. High-rpm 4V combos can use 1-3/4 to 1-7/8 inch. On the street, bigger isn’t always faster; sometimes it’s just louder. Finally, something to note is that EFI conversions… The giant 4V ports that struggled with fuel distribution in the ’70s suddenly make sense when you can meter fuel per cylinder. Throttle-body EFI helps, but multiport is where the manners really sharpen up — cold starts and part-throttle response. It’s like the Cleveland finally learned some table manners. Shop-floor showdown: Cleveland or Windsor? It’s an argument that’s echoed through garages for 50 years. Full disclosure: I’m a Windsor man myself, but bias aside, here’s the honest truth. The Windsor wins on practicality. Parts are cheaper and easier to find, and there’s a stroker kit for every budget. It’s lighter in many trims, the oiling system is simpler, and if you want plug-and-play street torque with everything on the shelf at Summit or your local parts store, the Windsor is a layup. It just works. The Cleveland, though, is pure Ford magic. Even in stock trim, nothing else in the small-block Ford world moves air like it. Those heads flow like race parts right out of the gate. The valvetrain stays stable at high RPM and the top end just keeps pulling when a Windsor would have already gone home. If you love an engine that wakes up hard from the midrange and keeps pulling long after a Windsor is tapped out, the Cleveland speaks your language. And yes, you can put a Cleveland in one of our trucks. If your rig had a 351M or 400, it’s a bolt-in deal — same family, same mounts. In an F-150 or Bronco that came with a Windsor or an inline-six, it’s more of a project: you need a rear-sump pan, custom mounts, and probably a Saturday or two of bracket bingo. But once it’s in, you have one of the coolest Ford mashups out there. When should you pick which? If your goal is around 400 treatable horsepower with good manners and minimal drama, the Windsor is easy mode: bolt it together, tune it, and enjoy it. But if you want a street-strip setup that feels like a small block pretending to be a big block, or you want the coolest Ford conversation piece in the parking lot, the Cleveland is your answer — especially if you’re running Aussie-style quench heads or a modern aluminum casting that brings the ports back to street velocity. Honestly, if my current build weren’t my first serious attempt at a truly streetable high-horsepower combo, the Cleveland would be awfully tempting. Someday I’d love to build a Cleveland just to remind myself why some Ford engineers in Ohio thought this crazy thing was the future. When De Tomaso dropped a Cleveland in the mid-engine Pantera, suddenly this blue-collar Ford engine was sharing poster space with Ferraris. It gave the 351C race-bred heads, an exotic sound, and European sheet metal. That combo made the legend stick — the Pantera made the Cleveland feel exotic. Those canted valve heads also changed how people thought about airflow and combustion. They taught a whole generation to respect chambers, velocity, and mixture motion. Quench stopped being a buzzword and became a philosophy. That’s why people still hunt for those two V-port quench chamber combos for street builds, and why the words Boss 351 still make people straighten up at car shows. The Cleveland didn’t lose because it was bad — it lost to its own era, emissions, and corporate politics. Cleveland disappeared. But was it so good it got cancelled? Not exactly. Its timing clashed with emissions, fuel, insurance, and corporate priorities, even though the design itself was excellent. The heads were revolutionary and the block was clever. With the right parts it is still an absolute riot. But the early ’70s weren’t kind to any engine, let alone engines that needed compression, cam, and clean fuel. The Windsor survived in the industry because it was simple and scalable. The Cleveland lives in our hearts because it was special. And that’s everything I know or pretend to know about the Ford 351 Cleveland engine. Have one, want one, or think I should dump my Windsor for a Cleveland instead? Think I should forget getting some aftermarket Windsor heads and build up a Cleveland instead? Drop me a line. If you have any other questions, comments, concerns, or gripes, drop them below. If you want to dig deeper into the builds, the side projects, and the stuff that doesn’t always make it on YouTube, or just want to get to know me better, come hang out on patreon.com/bullnose Garage. It helps keep the lights on, and I appreciate you being part of the garage. Thanks again for watching — we’ll see you next time.