I asked about 4-v heads in a previous post. My understanding was that there was no difference between 2-V and 4-V 302 heads in the casting, the difference was in the shape of the piston head and therefore in compression.
I have a set of heads I posted about awhile back. The air cleaner cover said 302 4v. It does not say 4V on top of the head. It says 302 and in a different spot it says B. Any ideas as to if it is a 4v? It is not a boss head.
The J code 302-4V was only made in 68. It was rated at 10.5:1 compression and 230 bhp(Shelby was rated at 250). The F code 302-2V was made from 68-73. The 68 F code had 10:1 compression and made 210 bhp. The 69 and 70 F code 302's are rated at 220 bhp. They dropped off after that. The 68 J and F code heads show to be the same in my information. The difference in horsepower was from a higher compression piston and the 4 barrel intake and carb.
There is nothing else special or different about these heads except that they have smaller combustion chamber sizes compared to later year 302 heads as Ford dropped the compression in stages. By 1972 the 302 had 8.5:1 which came from a combination of 58 cc chambers and lower compression pistons.
Technically there is no special 4V head that is different from a 2V head for a 302 based on what I know. If someone has different spec's for a 4V versus a 2V 302 head I will be glad to correct my feeble brain cells(after I see it, LOL).
I have an original 68 J code 302 mustang and can tell you positively that the difference between the heads is the 4-v heads have the small chambers 53.5ccs and the 2-v heads have the much bigger 63cc chambers (for 68 at least).
so what everyones saying is the 302 4v heads are really no better than 289 heads and the advertised 10:01 compression on 68 4v was obtained with these heads and a piston change.so i can't put a set of 68 302 4v heads on my 66 289 and gain any compression or other performance increase?