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4V heads have a "4" cast in the corner, 2V's a "2". 4V's intake ports are larger. If you want a good visual do a side by side comparison of intake manifold gaskets. The ports for the 4V are 1.88 x 2.65, the 2V are 1.50 x 2.12. As for the pro's and con's I'll let the experts cover that. Don't forget the quench and non-quench question in addition to the 2V vs 4v!
all Panteras equipped with U.S. sourced engines were equipped with large port "4V" heads of 2 varieties, closed chamber heads rated for 10.7 to 1 compression ratio (which was actually about 9.5 to 1) and open chamber heads truthfully rated for 8.8 to 1 or 8.0 to 1 compression ratios.

Once the DeTomaso source of U.S. built engines dried up, they began sourcing 351C engines from Australia. I believe these were all equipped with small port 2V open chamber heads.

As Husker wrote, American Cleveland heads had a "2" or "4" cast into one of the corners. Australian heads do not have such a number cast into them.

The good 2V heads from Australia are sourced from the Australian 302 cubic inch Cleveland engine, the 302C, because they had "closed" combustion chambers. Not all Australian 2V heads have closed combustion chambers, only the ones from the 302C. The exhaust manifold flanges on these heads have a larger cast & machined area around the port, allowing 4V exhaust manifolds to bolt up with no leaks, the American 2V heads do not share this feature.

Don't confuse heads from a 302C with the C302 aluminum heads sold by Ford Motorsports in the '80s.

Closed combustion chamber heads, either 2V or 4V, will allow running higher compression ratios with out detonation, than that possible with the open chamber heads. However, closed combustion chamber heads also produce more hydrocarbon emissions, which may be a problem for Pantera owners who live in states that require them to smog their cars.

Keep in mind, the ports of the "small port" 2V heads are still quite large for a 351 cubic inch engine. I've witnessed "Chevy guys" on more than one occaision, upon seeing their first set of cleveland heads, 2V clevland heads at that, say "Wow, look at the size of those ports!" They think they are looking at the big port heads.

Small port heads, lets specify the 302C heads, flow very well up to about 0.500" intake valve lift, after which the intake flow curve flattens out (hits a wall!) They exhibit very good low lift intake flow. The exhaust port, though smaller than the port in the 4V head, flows just as well, making the balance between intake & exhaust flow better with the 2V head. With porting & big valves, these heads are capable of supporting about 500 bhp. The drawbacks are the lack of flow improvement above 0.500" valve lift and the tendency for power to flatten out at about 6500 rpm.

The advantage of these heads is throttle response. anyone running an Edelbrock Peformer intake & 600 cfm Holley on their 4V Cleveland to improve low rpm response, would be better off running the smaller port 2V heads. Racers needing improved throttle response coming out of corners also turn to these heads in classes allowing only factory cast iron heads. These heads work well with 377 cubic inch stroker motors too. Intake manifolds available for these heads include the Edelbrock Performer 2V (idle to 5500 rpm), a Ford oem cast iron 4 barrel carb manifold from Australia similar to the performer(idle to 6000 rpm), the Weiand Xcellerator (1500 to 7000 rpm), the Torq-Power which is a high rise dual plane manifold from Australia, the Parker Funnel Web also from Australia, and Edelbrock's soon to be released Air-Gap RPM manifold which is similar to the Torq-Power. Larry Stock sells Pantera exhaust headers for the 2V heads also.

Engine builder opinions vary from 400 bhp to 500 bhp regarding which point to switch from small port to big port heads, but below 400 bhp and below 6000 rpm there is no argument, you are better off with the 2V heads.

On the other hand, the 4V engine can be built, with the right combination of intake manifold, carb tuning, camshaft & exhaust that will idle decently, pull smooth & mellow at low rpm and then hit the meat of the powerband from 3000 to 7000 rpm. Stroker motors lower that powerband to about 2500 to 6500 rpm. The stroker motor also helps the throttle response of the big port heads.

Last edited by George P

No the heads don't truly take the same exhausts, but there is an exception.

Keep in mind the 4V exhaust ports are much larger than the 2V exhaust ports. A 2V exhaust header will be too small for a 4V head. You end up with a large port trying to exhaust into a smaller "hole".

The 4V exhaust header is too large for a 2V head, the large flange of the 4V header doesn't have enough "mating-surface" on the head to make a good seal. The exception, as I mentioned above, the Australian 2V head has a very large flange around the port, so the 4V headers can seal up around the smaller 2V port. There is a port mis-match, you end up with a small port blowing into a larger open hole, not ideal for maximizing power, but it is functional.

Most headers are designed for the 4V heads, but I have heard that Larry Stock sells Pantera exhaust headers designed for the smaller port 2V heads.


(It is Doug, right?)

I'm reading you have a stock 351C, you want to replace the carb & intake. There are three major choices at this point, a '70-'71 oem Ford intake with a 600 cfm carb, the Edelbrock Performer with a 600 cfm carb or the Blue Thunder with a 700 to 750 cfm carb. All of these intakes are dual plane intakes with an exhaust heat crossover. The early model Ford intake is identical to the one on your car, but allows bolting up a "non-spread-bore" carb and has no provision for egr. The Edelbrock intake emphasizes lower speed operation which is at odds with the power band of the 4V heads and in my opinion also at odds with the car it would be installed in (Pantera is a sports car, not a truck or sedan). However, that is just my opinion, many Pantera owners run this manifold. The Blue Thunder intake operates from idle to 7000 rpm & is a very good match for the big port 4V heads. The Blue Thunder raises the carb about an inch, but your car has an egr plate between the carb & intake manifold, which also raises the carb about an inch, so without the egr plate the net vertical clearance will be about the same.

some questions for you to ponder:
(1)do you have any further engine modification plans for the future?
(2)what air filter are you going to install with this carb & intake?
(3)would you prefer to improve low speed driveability or increase mid-range power?
(4)how much fuss are you willing to put into this project? some carbs require tuning to work properly, not necessarily tuned by you, but you will need to have a pro tune it for you.
(5)what is the budget?
(6)do you mind removing the exhaust gas recirc system from you engine?

We should get together in ventura some time after the holiday.

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