OK, so we're in the middle of a 383 stroker buildup and the question
here is, roller cam or not? The engine is going to be used in a GMC
Sierra 1/2 ton 4x4 pickup which will be used mostly for towing and as
a daily driver. I'm looking for good freeway performance and the
extra grunt when towing. I suggested a roller cam and rockers to the
builder, but didn't want to be adjusting valves all the time. the
builder said he can get a roller cam and hydraulic roller rockers,
which will add under $200 to the cost, but will also give an
additional 25HP. We were looking at around 365-385HP and 425-435
pound ft of torque with standard hyd lifters and a mild performance
cam. I think the extra $200 is well worth the additional 25HP.
What say the engine guys here? Worth it or not?
First of all your torque hopes are a bit high because of displacement
and best towing perfromance usually means best possible lower to mid
RPM power/torque which does not play well with higher HP ratings that
need higher RPM torque peaks and curves to achieve them. Also vehcle
compression ratio, tranny type, tire size and axle ratio plays a big
roll in the best cam timing for desired useage as there is no
universal "works in all senerios" and anyone that tells you that it
does is blowing smoke. If your are seriuos about it being a good
tower, limit duration to about 260 degres (maybe 268 if your gearing
is proper) and plan on runniong at least 89 octane if you want to tap
its true potenail unless you aew running about 8.5 to one or less CR
because 87 will knock and one way or the other the spark curve will
have to be retarded and this will limit performance and MPG. It will
hurt you the worst towing too.
Your best bet is to call the experts. Crower, Crane, etc... all have
help lines you can call. Call them and ask, because there are a lot of
things to take into consideration. A cam can make compression or take it
away all with the valve timing. As long as you stay with a low end cam you
can make torque, look at what most big gas trucks use for an engine a 366
Big Block... a torque monster engine.
Please post what you go with and what you got out of it when you are done...
curious to see if you get close to your expectations.
P.S. it can be done... Jegs offers a ready to run 383 with 395 HP and 440
Roller cams and rockers dont need any ajustment so long as you use
hyd. lifters. I used CompCams roller lifters, cam, and Magnum roller
rockers in my 5.7 89 chevy. (Be aware that the push rod length will
need to be shorter with some set ups. Your brand of choice (Comp,
Crane, Crower, etc) should be able to tell you that). Chevy has two
types of cam thrust plates for the roller set up. For some odd reason,
the V6 uses a smaller one then the V8, but sometimes the V8 blocks
have the V6 version (Go figure). If the plate you get is too wide for
the holes, you need the V6 version. You might need bigger valve covers
for the roller rockers (CompCam magnums are smaller than those 'block'
type roller rockers, but you may still need to cut out supports for the stock
center bolt covers).
Roller set ups are so much better than flat tappet cams. I highly recomend it.
As far as the type of cam you need, that all depends on the tranny, tire size,
rear axl ratio. When you make up your mind as to who your going to use,
call them and let them know that stuff, and they will hook you up with a
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