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Original Message
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| Stock heads are better than the CJ heads. |
| By Dave Shoe - 07/07/2001 1:29:02 AM; IP 216.243.158.133 |
In your case (1965 and earlier), the stock heads will breathe better than CJ heads.
The 428CJ got the same intake runners, exhaust runners, and valve bowls as your heads, but the CJ also got restrictive Thermactor emissions bosses cast into the roof of the exhaust runner. Assuming you install CJ-sized valves in your stock heads, the CJ would have to have the emissions bosses ground out to flow equivalently. Note that CJ heads are cast for the common FE valve sizes but are throat dressed at the factory to fit CJ-sized valves.
The reason the 428CJ is such a hot engine is it got an MR-style intake manifold, and those suckers flow like crazy. It also got satisfactorily designed unibody exhaust manifolds, which is something the 390 unibody cars did not get.
If you are looking for some extra zip from your full-sized Ford, then you should focus on the intake manifold, cam, lifters, and valve springs. An Edelbrock RPM intake would suit you well (even with the port mismatch), and the cam kit will finish it off.
Headers are kind of a radical upgrade, but they'll buy you lots of HP once the intake and cam is in.
The tranny should be able to handle what you give it. It's not as sturdy as a C-6 (and not nearly as fun to work on), but it's a tough tranny. You might find that it'll need fresh clutch plates (a standard rebuild kit) if you start pumping extra horsies through it.
I have heard some claims that the FMX tranny will fall apart with any kind of abuse, but I'm learning these are apparently incorrect statements. One thing I do know about your tranny is that since it's design is based on a 2-speed Fordomatic that got an extra gear grafted on, that it's a rather complicated tranny to "learn" on, as far as doing a clutch-replacement. I've never had any problems taking them apart, but I still can't figure how to get them together again. I'm sure my difficulty is partly because I mainly take FMXs apart to claim the cool-looking mainshaft and I don't actually attempt to reassemble them because I only use a C-6 or toploader in my cars. Still, the C-6 is much easier for the first-timer.
Shoe. |
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