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Original Message
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| In general... |
| By Dave Shoe - 07/24/2001 7:27:20 PM; IP 12.2.11.131 |
...early '66 FEs (non-427) apparently came with either C6AE-J or C6AE-R heads. Later in 1966 you could find C6AE-R or C6AE-U heads on any FE. Early in 1967 the possibilities were C6AE-R, C6AE-U, and C7AE-A. Later in 1967 it was just the C6AE-R and C7AE-A. Due to stricter emissions laws, all these heads were replaced by the C8AE-H from 1968-1971.
I guess I can trust the source that claims the 1967 Shelby 428 engine only got the C7AE-A head, but I'm rather certain that some 428PI motors that year may also have been found with C6AE-R and C6AE-U heads. If someone else mentioned that some '67 Shelbys came with the C6 numbered heads, I'd tend to believe them. Ford seemed to install heads randomly into their motors - not recognizing any performance difference between the casting numbers Note that C6AE-U is identical to the C7AE-A.
In fact, any FE head is great for making up to 400 or so easy HP, but the C6AE-R is generally recognized as being a head that can handle more air flow. It's got the larger intake runner (like the 428CJ and all '65-earlier FE heads), and it's got the high-position exhaust runner (like the 428CJ, 427, and '65-earlier head).
As the 428CJ head is cast for standard FE valve sizes, and needs to be throat-dressed at the factory to fit the CJ-sized valves, the C6AE-R is basically identical to the 428CJ head except for the installed valve size and the combustion chamber size.
If open header operation or drag strip time is in your future, I'd go with the C6AE-R heads. All FE heads can make horsepower, it's just easier to do it with the large-runner heads.
Beware that C6AE-R and C7AE-A heads require different header flanges due to the different exhaust port positions. Use the low-position header flange (FPA-GT and maybe Hedman?) for the C6AE-J, C6AE-U, C7AE-A, C8AE-H, and D2TE-AA castings and use the high-position flange (FPA-CJ and Hooker) for the C6AE-R and all other castings. Note also the C6AE-R head has an anti-reversion lip on the roof of the exhaust runner where it mates to the header. Grinding this lip outta there will help high-RPM flow.
Note also that only the 1966-428PI got solid lifters. The 1967-later 428PI got hydraulic lifters. Also note that old FE heads can sometimes have somewhat sunken valves (due to multiple valve grinds or general seat wear). Installing oversized valves can frequently restore the position of the valve head back to the surface of the chamber, thus improving airflow and avoiding the expense of hardened valve seats to restore the height.
The Shelby Registry probably speaks about the 2-4V intake in accurate detail. Someday I gotta buy me that book. I suspect Ford would have installed the 2-4V intake at the factory, as these engines would have been specifically built for Shelby. This special build was necessary, as the unibody exhaust manifold bolt pattern was another unique "Shelby-only" item on those 428PI engines.
JMO,
Shoe.
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