cc volume is not important main diffrences where from factory with the amount of material removed to get a particular volume mine where 64cc closed chamber heads when i got them now they are 57cc, hope it helps you out i would also go for the 4v's forget all the crap you hear about them being a dog on the street a good setup combo is just fine, any engine can be a dog when poorly designed with incorrect parts..

if you can get a good set of cc 4v's for 950 i'd grab them, a good set will sell for 1200-1800 depending on condition of course 950 is very reasonable..

4V heads have they're place, but not on an everyday driver, 4V heads come in about 10 different variations from open chamber hydraulic thru to closed chamber mechanical with screw in studs, if you opt for the 4V heads you will have to buy a top of the line intake manifold such as the Jack Rousch (as already mentioned), and a cam that was designed for 4V's as the port size requires high lift and later timing to create decent vacuum.
Big cams & 4V's will also NOT pass emissions laws, and fouling plugs due poor idle circuit signal (vacuum strenght)
BUT when set up properly a 4V clevo can make 380-400hp for around $3500

They had lumpy top forged pistons & blueprinted engines heads were milled to around 12.6:1 or more!

11.1:1 comp is very close to just a CC head and stock 30thou down the bore. We got those engines here in Aus. They were imported from the US and fitted in our GT etc. In stock form these engines put out very close to 400hp stock. They even had solid cam's fitted from the factory.

All of the manual GTHO cleveland engines got them as most of the XY GT manual and the XA GT ,RPO83 got em but only the 1st 200 XB GT manuals got em towards the end of the 160mhp supercar era due to emission laws, thats when ford changed the code "4V" meaning the heads that were fitted, to the now commonly mistaken 4V, which denotes the number of venturi's that the carby has.
Ford did throw the remaining stock on the occasional car over the next few years until there were none left, or when the clevo died in 83, The 4V's i'm using on my latest project are original US imports with closed chambers 58cc & studs/guide plates as standard, they produced 581hp @6800rpm on the last engine, but power never dropped off until just over 8000rpm..... so be prepared to rev it to get the most out of them!

 

 

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4V inlet.jpg [ 27.43 KiB | Viewed 165 times ]

That's why you add cubes. No need to rev higher

It was stroked to 416, too!

this a a pic of my CHI 3V inlet and exhaust sides... less than a week till its finnished stay tuned for a a snipet of the first start up woohoo..

 

 

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File comment: CHI 3V exhaust IMG_0530.JPG [ 34.77 KiB | Viewed 165 times ]

File comment: CHI 3V inlet IMG_0727.JPG [ 198.39 KiB | Viewed 155 times ]