Here is another response from a frined of mine. He is currently on the
JEEP GC List and I am trying to get him on the Dakota list as well.
Tim May
>The one he was recommending was a dual pattern .512 .536 lift 206/212@50
duration(with 1.6 rockers).
Honestly that is pretty mild by Chevy smallblock standards. For example
the
emissions legal ZZ3 cam many Impala and F-cars are running has 208/221
duration, and that cam is considered totally streetable, if not fairly
mild
by some. The Magnum cam mentioned above seems tame by comparison, and is
an
outright wimp when compared to the 218/228 duration LT4 HOT cam some
people
are running in their LT1s. In fact the LT4 production cam is 203/210
duration, which compares well with the Magnum cam listed above.
That's not to say I don't like the specs of that cam (except I think the
lift is a little too high), in fact it should be ideal for a fuel injected
street engine, and should be compatible with the PCM, and it should not
require a great deal of PCM retuning to use.
Note that the stock 5.9 cam is supposedly 250/264 total duration according
to the service manual. To get duration at .050 normally you multiply by
.85, which would be 212/224! This sounds too radical for a production cam,
so I don't think it's accurate. I can't get any clear data on the
production 5.9L cam, although I do know it was beefed up for '98.
The factory "Magnum R/T" cam sold via the Mopar Perf. parts catalog is
204/208 duration at .458/.467 lift. Personally I think the .512/.536 lift
on the cam mentioned above is a little too radical, unless the heads are
ported to flow well at those higher lifts. It will beat up on the springs
as well as the rest of the valvetrain more, that's for sure. Personally if
I change cams I'll probably go with the Magnum R/T cam sold by Mopar Perf.
Then again I have always been a sucker for factory engineering. <g> The
one
thing that scares me is the PCM tuning, I don't know an Ed Wright or Ron
Zimmer who can do totally custom PCM calibrations like we can get for GM
PCMs, which would be needed for any more radical cams.
>They also do the necessary intake mods and throttle body work as well. He
said getting my truck in the 12s is no big deal(provided the traction is
there) , but I'll start breaking parts(namely the transmission and rear
end). This is what I was afraid of. I know I can replace the 8 1/4 with a
9
1/4 , but I don't know what to do about the NV3500. He told me to get in
touch with some Dak racers who are having their NV3500s modified.
I don't know what the NV (New Venture) 3500 trans is, my GC comes with the
Chrysler heavy duty 46RE trans, which is exclusive to the 5.9L engine in
the GC. All the 5.2L and below get the 44RE or 42RE, which are lighter
duty
(less torque capacity) transmissions. The 46RE is decoded as 4 = 4-speed,
6
= relative torque capacity, R = RWD, E = Electronic valve body. I thought
that same trans comes in the Dak 5.9L, while the Dak 5.2L versions only
get
the lesser 44RE.
>Perhaps I'll just do the headers, throttle body, milder cam and stage one
porting and se how the green monster does. What do ya'll think??.
I'd recommend the factory Magnum R/T package, which includes the cam,
headers (extrude honed manifolds would be my choice instead), exhaust, K&N
(either cone or stock type in drilled out airbox), and Mopar Perf. PCM. To
that I'd add the 1.6 roller rockers (they are probably 1.65 actual ratio
since they are made by Crane and that's normally how they do things), 160
thermostat, electric fan (I already have that <g>), underdrive crank
(only)
pulley, and mildly ported heads (available factory ported with larger
valves via the Mopar Perf catalog, list about $900 each). Scott.
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