[zreg]

Does anyone know where I can find information on the difference between the meaning of 4V and 2V? I thought this was a carburetor designation for 4 barrel and 2 barrel, but now I am not so sure. I believe that there is also a difference in port and valve size. I'm trying to figure out what I have in a 351 C engine. I was told it is a 4V, but I would like to find out how to verify this and understand the difference. Thanks

[Drgnracin72]

2v motors have 1 intake and 1 exhaust valve in the head per cylinder. the 4v has 2 intkaes and 2 exhaust per cylinder. im not sure about that 351. i dont know what kinda heads it has but i would guess a 4v head.

[Roadhawg]

In the past 2V and 4v use to stand for 2 venturi and 4 venturi, basicly the amount of Venturis the carburator had.....ie 2 barrel or 4 barrel.

[GTNorm]

I never heard of them putting a 2v on the cleveland engine although many of the windsors had 2v carbs . I could always tell the difference by looking in the top of the carb and if the butterfly covered 2 round openings t was 2v and In the 4v you have 4 round openings ,usually the 2 back ones are bigger. The c motor also had small spark plugs while the w motor has the big plugs.

[Bossman351]

There is a HUGE difference in 2v and 4v heads on a cleveland. The ports on the 4v head are much larger for starters. A 4v manifold or header will not seal on a 2v head b/c the port on the 4v part is bigger than the entire mounting surface on the 2v head. I made a set of aluminum adapter plates to make a set of 4v headers work on a 2v head but you have to use longer header bolts and its a PITA to get them in there. Same deal with the intake runners. The bolt holes line up but the port on a 4v intake is much larger than the ones on a 2v head.

Also, Roadhawg hit the nail on the head. In old school terms the v stood for "venturis" or barrels in the carb. Nowadays it stands for "valves" as in valves per cylinder. The 2v heads would have 1 intake and 1 exhaust valve per cylinder and the 4v heads would have 2 exhaust and 2 intake valves per head.

[mdvaldosta]

Yea, 2v vs 4v are completely different when talking about the 351 clevelands or late model 4.6's (as drgnracin72 was talking about). Like the others said, on the Clevelands it had to do with the heads. The port sizes on the 4v were huge, way too big IMO. The 4v Cleveland heads came with 4 bbl carbs (pretty sure they all did).

It's confusuing, they shouldn't have used 2v and 4v to designate Cleveland engines.

[zreg]

Well, the vehicle came with a 2V, but it was modified to a 4V. What I don't know now is how to tell the difference between a 2V or a 4V head without taking the exhaust manifold off and measuring the ports. This would not be a big thing, but I decided to purchase a performance intake and carburetor and these are different depending on heads.

From what I have researched, 2V and 4V correlate to carburetor barrels and on the 351C, they used different heads for both engines. There is no early model 4 valve configuration (2 intake, 2 exhaust) for the 351C. There seems to be a lot of debate on whether 4V heads are better street performers than 2V heads, but regardless, it would be nice to figure out the how to tell what I have without taking the manifold off.

[Horseshoeing]

Can you give me the # on the heads? It should be something like DOAE , D1AE , D3AE , D32E , D4AE

[zreg]

I could not find the casting numbers. but I did find that the number "4" is cast into the upper right and left corners of each head, just outside the valve cover gasket perimeter. I'm pretty sure that this means they are 4V heads. I take it the casting numbers are under the valve covers?