351C 2v to 4v

[dbgrigsby93]

My 1973 Mustang Mach 1 has a 351C with a 2v carburetor. I would like to change from a 2v to a 4v but I would like to know if I iwll have to change the heads right off or if I can get a 4v carburetor and use with the stock heads until I can come up with the money to get new heads. I've heard the engine won't run right if the carburetor is changed and heads are left and I've also heard that the engine will run fine if the carburetor is changed and the heads are left. However, my source saying the engine will run fine is a little more credible than the other source. This is from http://www.vintage-mustang.com/topic...leveland.html: "The 351 Cleveland, on the other hand, belongs to Ford's 335 engine family. This thin-wall cast BIG SMALL BLOCK uses the smaller 14mm spark plugs, has a separate front cover (bolted to the block) housing the timing chain and routing water - so that water does not go through the intake manifold, features beefy main caps (wide enough to drill for 4-bolt mains), a poor oiling system, and uses different heads for 2V & 4V versions. The heads make all the difference and these fire breathing babies make this motor the legend it is. On the 4V, the valves are HUGE, measuring 2.19" intake and 1.7n" exhaust (don't remember exactly). Valves this large are only possible via a canted valve arrangement, forming what Ford refers to as a "poly-angle" combustion chamber. The valve covers are not straight - the front is flat and parallel to the ground, but a curve twists the rear parallel to the head. They are attached by 8-bolts and when removed, there is a 4 cast into the corner of the 4V and a 2 cast into the corner of the 2V (at least in 1970). The canted valves are the dead giveaway." If someone can speak from experience on this, I'd appreciate it. I intend to change the heads on my car eventually anyway but my budget limits me to doing one thing at a time.

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[THUMPIN455]

You can get a 4 barrel intake for the 2V heads, you can also find 4V heads and get intakes for them as well. Edelbrock and Weiand both offer intakes for the 2V heads, and the 2V can still make very good power with very little effort.

I have 2v and 4v Clevelands, the 4v are faster but the 2v is no slouch either. The ports are very different in size. 4v on the left 2v on the right.


You can put a 4v intake on the 2v heads, but its better to get the intake that fits the ports since they are available now. The Cougar in my sig has a 2v Cleveland in it, havent run this one yet but it should be quite fun.

[nassaubayman]

I once owned a '70 Cougar XR-7 convertible with a 351-C 4V. A previous owner replace the motor with a rebuilt long block that came with 2V heads. I had the original 4V intake with large ports pushing fuel into heads with small ports. The car had a noticeable studder at freeway speeds.

If you bought a 4V intake that fits the 2V heads, you'll be wasting you money if you intend to upgrade to 4V heads in the long run.

Like Thumpin said, the 2V heads are no slouch. Unless you're having issues with your current carb, I'd recommend you leave it alone until you can afford to do the complete upgrade.

[69mach1377]

The point is to match your intake, heads, cam, carb and exhaust to meet a performance level. Enlarging only one may not make much of a difference, or even two for that matter.

[1971mach1]

I have read on several sites that the 2V heads with a matching (aftermarket) 4bbl intake actually is better for the street because it makes more low end torque.
Unless you're going to do some serious high-rev drag racing, I would just get a 4bbl intake ment for your 2v heads and spend the money elsewhere.