Mailbag: Ford Cleveland 2V vs. 4V Cylinder Heads
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.
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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.
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
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