Fordnatics List Archive

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Mail From: "Obermann Mark" <(email redacted)>

Hello,

I have come across a pair of 428CJ heads that apparently were extensively
ported on the intake side. Apparently, these heads flow nearly 75% more than
stock. The exhaust was basically left untouched. Now the questions. Will
the increased intake flow be useful with the stock PI/CJ intake? Will low
rpm drivability suffer? Should I have the exhuast ports and exhaust
manifolds ported for better flow or is this not necessary? With the exhaust
manifold, I guess the only way is with Extrude-Hone, but that process is very
expensive. Don't want headers. Finally, is there a better exhaust manifold
than the stock CJ manifold that still fits in 69 Mustang engine compartment?

By the way, the engine is for a high performance, very streetable street car.
Thanks for any and all your help.

Mark

(email redacted)

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Mail From: (email redacted) (Jay Fletcher)

FE heads have notiriously poor exhaust ports (al pinched and twisted) as
do MOST Ford heads (Clevelands being an extreme exception). The porting
work should have BEGUN on the exhaust side. I doubt the 75% increase on
the intake side is helping much without porting the exhaust.

Jay

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Mail From: "Fontana Peter" <(email redacted)>

Jay says:
> I doubt the 75% increase on
> the intake side is helping much without porting the exhaust.

Mark -
Let me take that one step further: You are limited by your exhaust system on
that motor even with stock heads. Although the CJ 'folds are the best
available for the early 'stang, they will still be the limiting factor. If
you want to retain these manifolds, then open the rest of the system the best
you can (nice 2.5" pipes with 2 good mufflers - no transverse), and at least
check the manofolds for casting irregularities you can grind away. I doubt
you'll be able to realize the full power of any mods that make power above
5500. Head porting definitely falls in that category. I'd bet stock heads
on your motor now would provide more lower end torque than what you've got
now, and those ported heads can't do much up high through those manifolds.
You'd do better with headers...

Can you be more specific about what your power goals are? If you just want
some more grunt down low, then one path can be taken (keeping the CJ exhaust
manifolds). BUT - if you want to hit 450+ HP at 6300 RPM, then let's get the
rest of the head work done, dump the juice cam, get headers, ...