Q: I’ve found that many of the best intake choices for the Ford 351C are for the engine with 4V cylinder heads. What is the biggest difference between the 2V and 4V heads? I know the valves in the 4V heads are bigger, but what other differences are there? Can the 2V head be machined to 4V specs, and can a 2V engine block be drilled for use with a 4V intake?
A: Starting with the basics, 2V heads are designed for use with a factory 2-barrel carburetor option (2V = 2 venturi), while 4V heads came on one of the five Ford 351C engine configurations that came with a 4-barrel carburetor (4V = 4 venturi). The biggest physical difference between the 2V and 4V Cleveland heads is the huge intake and exhaust ports on the 4V heads. There simply isn’t enough material around the smaller 2V ports to hog them out to mate to 4V port dimensions. Since all Cleveland blocks are the same, you can swap 2V heads for 4Vs and vice-versa, but you’ll also need to make sure you have the right exhaust manifolds/headers to match.
There are some good 2V intake manifolds out there. If you want a dual plane intake, the Edelbrock Performer is a good choice. It builds power from idle to 5,500 rpm. If you want a single plane, get the Weiand X-Celerator. It builds power between 1,500 and 7,000 rpm.
…
the performer rpm is even better
And please note that the 2 mentioned, and most other, aftermarket intakes utilize 4 barrel carburetors.
RPM Air Gap is even better! Fits both 2V and 4V
The price difference is huge between the two heads also. Can get 2V heads for a few hundred bucks… the 4V heads will cost you a couple grand. I had someone offer me 1500, a 429 cj block and heads for my 4v’s, and I said no.
I have a set 0f 71 4V heads. Last offer I turned down was $3000
I also have a set of 73 police interceptor heads.
Will not ever sell any of these heads. Way too hard to get anymore.
Is he still looking. I can definitely hook him up!
Is he still looking. I Have a couple sets!
The Ford 351C or Cleveland as it is known because its parts were cast at the iron foundry located in Cleveland Ohio, is a very unique and often misunderstood engine. The confusion is usually centered around the cylinder heads, beginning with the 2-V and 4-V designations. As previously mentioned, the “V” means venturi or “barrel”, which is a path of flow for the air/fuel mixture in a carburetor.
Many modern engines such as the popular Ford Coyote have 4 valves per cylinder and use “4-V” in the description. So it’s easy to see why a younger automotive enthusiast might mistakenly identify the carburetor venturi numbers with the number of valves in a cylinder head.
The most noticeable difference between a 2-V and 4-V Cleveland cylinder head would be the port sizes. The 2-V has 2.02″ x 1.65″ intake and 1.84″x 1.38″ exhaust ports. The 4-V heads designed for four barrel induction systems have much larger 2.50″ x 1.75″ intake and 2.00″ x 1.74″ exhaust ports.
Naturally the 4-V heads have larger valves to match the increased flow capacity of the ports and 4 venturi carburetor. Both head designs can be used for high performance engine builds but serious attention must be used when selecting all components in order to match the performance characteristics of the two different head designs.
The blocks used for 351C engines produced in the United States are all the same with the only exception for some being the crankshaft main bearing support caps. All production blocks are equipped with 5 main bearing support caps. Most caps use 2 bolts for attachment to the block but all Boss 351 engines and most of the performance “Cobra Jet” 351C blocks used 4-bolt main bearing caps for additional strength. The 2-bolt blocks are very strong as produced but can easily be machined to accept 4-bolt caps if desired.
Prices for used cast iron production blocks and heads will vary according to the condition and type but for $2000, brand new aluminum alloy Cleveland heads are available from Summit Racing.
4V?? Way too big in every way. What were they thinking! No low down airspeed. Maybe ok if you run the engine over 7000 but then the poor oiling has the engine explode!
The US 2V heads have the larger 70+cc chamber [as do most 4V] so will always be a little docile. Us Aussies had the 302C heads with small chambers starting around 59cc. With a little tidying up you can get 11-1 and will have a very torquey driveable engine. And make a real 500hp without trying too hard
Hello Lee,
Your statement/question of “ 4V ?? Way too big in every way. What were they thinking ! “.
The obvious answer would be winning races. By looking at the production 351C 4-V port dimensions listed in my previous post, it’s clear to see that the Ford performance design engineers had enough information about the changes that were coming, and DID come in NASCAR about the plans to eliminate big block engines from competition in the very near future in favor of small block engines.
Ford Racing was staying ahead of the game by producing the Cleveland 4-V Engines and getting them on the streets in sufficient numbers to satisfy the mass production rules set by NASCAR.
Unfortunately, in order to make this small block engine with such wide cylinder heads fit between the narrow shock towers of the Mustang while also keeping the factory production line costs as low as possible, they had to start making design compromises which would also have detrimental effects on power output.
The exhaust port design was the most obvious. For exhaust manifold clearance, the port has to take a sharp downward turn which left a large portion of the port floor practically useless in terms of exhaust flow velocity. It was a restriction so critical that overall it also hurt back up into the intake ports.
But the head had too much good potential to just write it off. The heart shaped closed (quench) combustion chamber was designed so well that it was recognized then as well as now as being excellent in terms of power production efficiency. So to correct the compromised exhaust port, the “high port” exhaust port plate conversion was developed. It effectively relocated the port exit higher which eliminated the sharp downturn of the production port giving the exhaust a straight shot from the valve to the port exit.
With that issue out of the way, racers could now enjoy the big port/ valve Clevelands with the advantages of extended rpm levels. That’s when another minor problem became apparent. The misinformation online spread by uninformed idiots made it all much worse than it actually is. But the oiling systems of production blocks were designed to reduce cost during the Ford machining process by omitting a third large oil gallery. For Stock or mild performance engine builds, the production oiling system will handle the rpm requirements just fine in most cases. But when the Pro Stock guys started enjoying the Cleveland advantage of having race winning power the other competitors didn’t at 10,000 + rpm’s, that’s when the oiling system shortcoming suddenly became a problem.
If the online experts have you convinced to stay away from Clevelands or EXPLODE !!! Just relax because the fix is simple and inexpensive. The most cost effective fix is easy and commonly available. Screw-in oil restrictors used in select oil passages within the block bearing saddles limits oil flow to the upper engine and valve train and keeps it consistently to the main bearings.
For a few bucks more and in my opinion, the best overall way to control excessive oil flow to the valve train is to use brass alloy lifter bore bushings for all 16 lifter positions. Its best done while your block is in the competent hands of a machinist during the phase of standard machining always done before a rebuild.
Just gather up as much of the one thing that’s getting harder to find before beginning any build…COMMON SENSE !!!
Your pride and joy might still explode. But it sure as hell won’t be a result of that dangerous oiling system that the online experts warned you about.
And the beat goes on….
not the problem we aussies had,
the pick up was in the wrong place causing oil starvation
I agree with Lee. 4v runners are way too big. No velocity at low down speed. The air gets lazy and almost lost in such a big runner. The key work is velocity and you must component match cam profile with everything else. Yes (what were they thinking!!!)
I have a complete 351C 2v (not sure what year) and a 1971 351C 4v block, heads, and manifold. Looking for some opinions, should I leave the 2v as is or swap the heads and manifold? It’ll be going in a 69 Torino GT and driving on the street
For you guys still interested in the Cleveland engine family, these heads still or did belong to the small block Ford engine family. We raced these engines back in the 70s through the 80 in our Dirt Late Model. The heads themselves have the same deck bolt pattern of the 260,289,302 and the 351W Windsor plant engines as well as the Cleveland plant engines. With that said water ports out are different with the Windsor in that the coolant comes out though the intake face of the heads on these Windsor engines. We have in the past modified these heads for Windsor block based Boss 302s. The big thing is that the 4V engines have truck drive though intake ports that make this a high rpm engine, the exhaust ports were so so to really get max HP you needed to the High Port conversion. This involved milling most of the exhaust port off the head and fitting an aluminum plate with a port angled upwards from the original angle of the port the head bolts when though these plates and they were also machined for the spark plugs to fit though. Oiling was kind of an issue as stated buy a guy before, oil in the C block went though the lifter gallery and if you bent a pushrod or had a lifter problem it would be an issue, we cleaned the bore and oversized it also drilled and taped the valley to put a plate over the lifters so you could not loose one. We also fed oil though both ends of the block with a Melling oil pump with a 100 pound relief spring in it for the wet sump, Dry sump was pretty much the same. Restrictor plug in the cam and opposite lift gallery too were used. Our power band was from 4500 to 8500 back then with the 4V heads, in the early 80 Ford came back into racing with SVO and we switched to the Ford SVO heads. I am working on one last engine I kept that I am putting stock 4V quench chamber heads on for old times sake should be a really good sleeper engine. Cheers, Steve at METECH Engneering
Steve, thanks for the information. There’s obviously still a lot of old school Cleveland builders like myself, and many younger builders that are totally burned out on the the same old SBC and LS builds with the same results. Less than spectacular performance in modern times when performance can and should be something to get excited about.
Giving credit where it’s due, the modulars like the Coyote and Voodoo offers performance from the factory that’s fantastic. Add your favorite flavor of aftermarket goodies and easily double the already mind numbing power production.
But interest is definitely on the rise for Cleveland fans worldwide. Just look at the impressive number of new performance parts available now with even more coming in the future. Australia has a huge following and strong aftermarket support for Clevelands. Heads from CHI, AFD, Scott Cook and more from down under. I will also mention the Arrow alloy block for Clevelands too because it’s a pretty good piece but shipping to the States makes it a very costly deal. But for those that don’t know the good news, listen up.
There’s reproduction 351 Cleveland blocks being manufactured and sold right here in the USA. They are available in various iron alloys for different strength requirements. And of course aluminum alloy is available to save considerable amounts of weight from the front of your favorite Fords. The really cool thing common to all of these blocks is they feature full Cleveland architecture, meaning they look almost identical to the factory blocks right down to the Ford part and casting date. Plus bolt on exterior parts from the factory or aftermarket are fully compatible so anything from your original engine will bolt onto your new aluminum block Cleveland engine.
Besides the Aussie Heads, there’s a good selection of American made heads from Edelbrock and Trick Flow too.
But the best news is the blocks because the supply of good usable block cores is rapidly shrinking everyday. Back when the Cleveland engine dominated Pro Stock and other classes of drag racing , some teams would use up 2 or 3 blocks each race. They had to use stock production blocks almost exclusively because the aftermarket acted like they never even heard of Ford. The competition felt the same way every time a Small Block Cleveland Ford kicked their asses around the moon and back !!!
Check out the websites for full block details.
American made Track Boss Blocks and more at;
tmeyerinc.com
American made Titus blocks and more at;
titusperformanceproducts.com
I had a 72 mach 1 with a 351c 2v my alternator bolt broke off in the block so I sent the heads in to get the problem fixed and when I picked up my heads the guy told me I could of just take the right side heads and put them on the left side because there was an alternator old on the back side of drivers side heads…fact or fiction?
Fiction
Ford put a lot thought into the 4V heads. The port and valve sizes were designed to deliver a wide power band and are divorced from standard high speed flow logic. Actually advanced beyond the old high flow logic. If you do not understand why they are the size they are then you need to get educated. Ford engineers were well ahead of their time. And 4V head design was very deliberate and would be optimized by a 377 cubic inch stroker. If your 4V engine has soggy bottom end it’s not due to Ford port engineering it’s due to you not understanding how to optimize the design with cam timing, intake runner design, carb size, static MIN 10:1 and dynamic compression ratio 7.70:1 and most of all an LSA of 112 to 114. Go below 112 and the bottom end will suffer the large ports amplify LSA. Close the intake valve by 70° ABDC. Open exhaust valve by 80° BBDC. Max 62° of overlap. Hydraulic intensity of 50-62 and lift .550 to .600. Short 2 1/2″ exhaust with X crossover. Crane HR216 Hyd roller.
Douger,
Would like to discuss a 351c with open chamber, that is in a Pantera.. had a friend that had one and was disappointed with the bottom end like you mentioned.
yes but you are not mentioning the difference between the closed chambered and open chambered heads
Those 4v beast would be good for boosting. 871 or twin turbo. Depends if you want to munch Bow ties with a fork or a spoon. Lol
All the north american Cleveland engines by year & VIN code. Compiled fr original, period correct, OEM Ford publications.
1970: VIN H; 351 2V, 2 bolt mains, flat top pistons, 9.5:1 compression using 76.2cc (averaged) open chamber heads, small ports, 2.04 intake/1.65 exhaust valves, 250 gross HP @4600 rpm, 355 ft lbs gross torque @2600 rpm.
1970: VIN M; 351 4V, 2 bolt mains, flat top pistons, forged steel connecting rods, 11:1 compression using 62.8cc (averaged) closed chamber (quench) heads, large ports, 2.19 intake/1.71 exhaust valves, slightly better cam & valve train, 300 gross HP @5400 rpm, 380 ft lbs gross torque @ 3400 rpm.
1971: VIN M; 351 4V, 2 bolt mains, flat top pistons, 10.7:1 compression using 66.1cc (averaged) closed chamber (quench) heads, large ports, 2.19 intake/1.71 exhaust valves, slightly better cam & valve train, 285 gross HP @5400 rpm, 370 ft lbs gross torque @ 3400 rpm.
1971 (late): VIN Q; 351 4V, 2 or 4 bolt mains, flat top pistons, 9:1 compression using 75.4cc (averaged) open chamber heads, large ports, 2.19 intake/1.71 exhaust valves, Cobra Jet cam, spread bore carburetor, 280 gross HP @5800 rpm, 345 ft lbs gross torque @3800 rpm.
1971: VIN R; 351 4V BOSS, hi nodular iron block w/ 4 bolt mains selected for hardness, selected hi nodular iron crankshaft w/ special damper, forged pop-up pistons, conrods shot peened & magnafluxed w/ 180,000 PSI bolts, 11.3:1 compression using 66.1cc (averaged) closed chamber (quench) heads, large ports, 2.19 intake/1.71 exhaust valves, solid lifter cam & valve train, 750CFM Autolite/Motorcraft 4300D spread bore carb on hi-rise aluminum intake, 330 gross HP @5400 rpm, 370 ft lbs gross torque @4000 rpm.
1972: VIN M & Q; same as ’71 Q except for camshaft retarded 4 degrees, 266 net HP @5400 rpm, 301 ft lbs net torque @3600 rpm.
1972: VIN R; 351 4V HO, same as ’71 R w/ the following changes; forged flat top pistons, 9.2:1 compression using 75.4cc (averaged) open chamber heads, solid lifter cam (retarded 4 degrees) & valve train, 275 net HP @6000 rpm, 286 ft lbs net torque @3800 rpm.
1973-74: VIN Q; 351 4V, 2 or 4 bolt mains, dished pistons, 8.2:1 compression using 78.4cc (averaged) open chamber heads, large ports/small valves, 2.04 intake/1.65 exhaust valves, Cobra Jet camshaft retarded 4 degrees, spread bore carburetor, 248 net HP @unknown rpm, unknown ft lbs net torque @unknown rpm.
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