is the difference between 4v engines and 2v engines the number of valves per cylinder or is it 4 barrel or 2 barrel carb? Just wonderin

 

They're talking 2 or 4 barrel...the heads on a 2v engine will have smaller ports and runners that flow the fuel into the cylinder and the runners will also be smaller on the exhaust port...so if you get a 2v engine and slap a 4 bbl carb on it, you won't be able to use the full potential of the carb unless you somehow open up the ports and runners on the head.

 

The valve sizes for the 351w has not varied much since it's inception in the late 60's. The earlier heads had 1.84 intakes and 1.54 exhaust valves with the sizes dropping to 1.78 and 1.45 after '77. I believe the port sizes were slightly larger on the earlier heads too. I believe the same heads were used on both 2v and 4v Windsor engines.
Now there were different heads for 2v and 4v Cleveland engines, with the 4v heads flowing so much that they were overkill on the street and best suited for racing. Even the 2v Cleveland heads would probably flow better than alot of aftermarket heads for the Windsor. It used to be real popular for the racers to take the best each engine had to offer and bolt Cleveland heads onto a Windsor block resulting in the "Clevor". A special intake and some minor machine work was necessary to do this.
DannyP

 

I checked the differences when I got my long block 351W...the heads have different port sizes on the 2Vs vs the 4Vs stock...I didn't check the valve sizes though.

 

>They're talking 2 or 4 barrel...the heads on a 2v engine
>will have smaller ports and runners that flow the fuel into
>the cylinder and the runners will also be smaller on the
>exhaust port...so if you get a 2v engine and slap a 4 bbl
>carb on it, you won't be able to use the full potential of
>the carb unless you somehow open up the ports and runners on
>the head.

I disagree with the above statement. I believe the 351W has no difference between the runners on the 2v and 4v from 69-80. Both intakes should have 1.82"x1.02" ports and there were no 2v or4v heads on stock engines with the exception of some performance parts. Stock heads should have 1.94"x1.76" intake and 1.24"x1.00" exhaust.
I'm not to sure about the newer engines, correct me if I'm wrong.


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Well, I'm just going by what I was told and I haven't compared them...but, when you order the long block, you can get one with the 2V heads and one with the 4v heads and my mechanic (seems real knowledgeable on Fords) told me about the different size runners on the intake. The 2v heads are supposed to also have a larger combustion chamber which would give you lower compression.

Slik

 

Oh, by the way, mine was a 351W for an '82 if that makes any difference.

 

[updated:LAST EDITED ON 16-Dec-01 AT 11:23 PM (EST)]I looked this up in my book and this is what I get out of it.

There was not a special 351w 4v head. The difference in 4v or 2v was the piston which raised the comp ratio. 2v and 4v both had 60.4cc combustion chamber size.The last 351w 4v engine was made in 1971. The difference in port size that has been talked about may be from the later 77 heads and the earlier heads. The earlier heads had L-shaped water passages that accomodated an extra intake manifold bolt in the 351w intake. During 1977 and later, 302 and 351w heads were basically the same, with 69cc combustion chambers,and no extra bolt, and looking at the picture, do seem to have slightly smaller ports than the earlier 351w heads. I suppose the only difference in the 77 and later 302/351w heads are the head bolt sizes.

351w heads up to 77 had 1.84" intake and 1.54" exhaust valves. 77 and up 351w heads, had the same valve sizes as the 302. 1.78" intake and 1.45" exhaust.

 

>I looked this up in my book and this is what I get out of
>it.
>
>There was not a special 351w 4v head. The difference in 4v
>or 2v was the piston which raised the comp ratio. 2v and 4v
>both had 60.4cc combustion chamber size.The last 351w 4v
>engine was made in 1971. The difference in port size that
>has been talked about may be from the later 77 heads and the
>earlier heads. The earlier heads had L-shaped water
>passages that accomodated an extra intake manifold bolt in
>the 351w intake. During 1977 and later, 302 and 351w heads
>were basically the same, with 69cc combustion chambers,and
>no extra bolt, and looking at the picture, do seem to have
>slightly smaller ports than the earlier 351w heads. I
>suppose the only difference in the 77 and later 302/351w
>heads are the head bolt sizes.
>
>351w heads up to 77 had 1.84" intake and 1.54" exhaust
>valves. 77 and up 351w heads, had the same valve sizes as
>the 302. 1.78" intake and 1.45" exhaust.

I assume you are getting your information from a book called "High Performance Ford" by George Reed? I also have that book and I 'm pretty sure that's where I'm referencing my earlier post.
I was searching for information on the legendary 4V heads too until I read his book. So I just decided to use and aftermarked manifold and carb, since I have the early heads.

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I was using "How to rebuild your small block ford"

 

Yowzer, I cracked open the books last night to take a look at the 4V/2V differences. Now, I'm really confused. I agree that all of the chamber size and port size information I received from my mechanic was basically wrong. Here's what I found (from "How to Build Small Block Ford Engines":

351W heads from '69-'76 the combustion chamber was 60.4 cc's with 1.84/1.54 inch valves

Ford started to phase in 69 cc combustion chamber heads in '77 with 1.78/1.45 inch valves

It appears the intake ports were all the same size with differences in water passages and air pipe passages depending on the year....But here's the kicker...The compression ration on the 4Vs was a point to a point and a half higher than the 2V versions when checking the chart for "Compression Ratio/Cylinder Head Interchange"...so, I assume that the difference in compressin ratios must have been from the shape of the piston dome!!???

Now the 351C has a dramatic difference in the intake ports between the 2V and 4V, so that may have added to the confusion.

 

in reference to a statement made above with the 351c heads with 351w heads put on it weren't the cleveland and the windsor 2 different blocks i believe the 351w was actually a 302 block and the 351c was actually the same block as the 360 and was a big block not a small block and the 2 are not interchangeable with each other.
Correct me if I am wrong

 

Yes the 351C and Windsor are 2 different blocks, but either by dumb luck or on purpose they both have the same bore spacing and headbolt pattern and for the most part the water passages are the same. The minor machine work I mentioned was some alterations to water passages. I am not real sure of the details but I can find out if you are interested. It is not as popular a setup anymore since the aftermarket has started supporting the 351W with good flowing heads of it's own.
DannyP

>in reference to a statement made above with the 351c heads
>with 351w heads put on it weren't the cleveland and the
>windsor 2 different blocks i believe the 351w was actually a
>302 block and the 351c was actually the same block as the
>360 and was a big block not a small block and the 2 are not
>interchangeable with each other.
>Correct me if I am wrong

 

AZ4x4f150 , look how the engines are grouped together in the forum headings on this message board. It will give you some clues as to what is related. The 360 is definitely not related to the 351c. If you get ford's engine lineup figured out, you will be way ahead of most people!

 

>in reference to a statement made above with the 351c heads
>with 351w heads put on it weren't the cleveland and the
>windsor 2 different blocks i believe the 351w was actually a
>302 block and the 351c was actually the same block as the
>360 and was a big block not a small block and the 2 are not
>interchangeable with each other.
>Correct me if I am wrong

The 302 and 351 are not the same block. They do share bore spacing, mount locations and bolt patterns. The 351 is 1" taller and uses larger mains.

The 360 is the ooooold FE block, no relation to a C.

The C block is different but as stated, the heads will interchange with Windsor heads and vice versa.


And while Ford doesn't "officially" use big block and small block, the C would be a small block because of the bore spacing shared with 302/Windsor motors.