Ok Shane....(How did I know you were going to jump in on this one) ;)
The 5-10HP from the Rollers (as Crane and Crower techs stated...at least
from their Dyno runs) isn't that big of an increase for the money spent.
But...to those few tenths of a second...ok, it counts. I run 1.6:1 Rollers
for the added safety and less resistance, but the Dyno runs didn't sho any
difference at all. AND...on a buddies Dak who has the 1.7:1 rollers, 7HP
difference...with only the roller rocker swap.
As for the higher RPM safety, I've blown my share of stamped steel rockers
in the past and a few pushrod dents on the valve covers. Why...because the
stock stamped steel rockers (to put it in plain english) "suck". As for the
lifters, the "Hydraulic Roller Lifters" that our engine use, Crane is
working on a lighter weight design as we speak (yup...spoke with their
techies last Friday but it won't be for at least 6 months from now if not
later...they said something about Mopar, rights, and designs).
Taking a small-block Mopar (in stock form) up to 6000rpm is just plain
stupid...no arguments from me on that one. However, they can be built to
withstand (in stock block form with mild "massaging") higher RPM's...up to
6500 without problems on the last 340 we had built in my old shop bosses
Dart. BUT...no stock rockers, pushrods, lifters, valve springs, keepers, or
locks on that valve train. (Then again, that wasn't a Magnum engine
either.)
Hey, it's a list where the "700+" members read each others responses,
formulate their own decision, and buy the parts they want. We can quote
articles out of various magazines and reference manuals all day...but it all
boils down to what works on the street and what doesn't.
Going back to my movie now....
Later Y'all,
- Bernd
----- Original Message -----
From: "Shane Moseley" <smoseley@ix.netcom.com>
Subject: Re: DML: Re: Lower Gears and Highway Cruising
> Say what? Surely you jest. 1.7 to 1 rockers -vs- 1.6 to 1 don't add much
HP?
> Bone stock maybe not that much but for an engine that has been modded to
intake
> more air (upgraded air filter/inlet & throttle body) and exhaust more
gases
> (headers, high-flo cat, cat-back exhaust) I'd say it makes a nice
difference in
> HP. It would be like a camshaft with the same duration but with higher
lift
> because it has the EXACT same effect - raises the valve slightly higher on
every
> stroke to allow more breathing capability.
>
> As far as added safety if you happen to "Over-Rev" the engine - hardly.
> Aluminum ones might absorb some valvetrain harmonics over the stock
stamped
> steel ones and possibly keep the valvetrain geometry slightly more
accurate but
> there are more serious things to consider. I quote the following from
Mopar
> Muscle - July 1997 issue - article titled: "Inductive Reasoning"
>
> "The other concern centers around the lifters. They're real heavy and
overcome
> the strength of
> the lifter bore casting at high RPM. Spinning a Magnum to 5400 RPM is
> borderline, 5800 RPM too
> much, and above 6000 RPM can be the kiss of death. What happens is the
heavy
> lifters crack the
> casting, start to wobble and the valve train self-destructs. When the
valve
> train starts to go
> bonkers, you'll notice an upper RPM vibration, almost like the engine is
out of
> balance. Either
> limit your shift points, buy a Fluidampr, or pray somebody develops a
> lightweight lifter for the
> Magnum."
>
> No known upgrade will help this problem. This is also the reason lots of
people
> have to re-bore
> and sleeve the lifter bores (costly). Very common on Mopar small-blocks
due to
> this design
> flaw. If you have ever seen a bare shortblock (any year smallblock will
do) -
> it isn't hard to
> see where the weakest part of the whole block is - the lifter galleys.
Compare
> them with the
> race version block from MP - almost all the difference is there.
>
> If you are going to put technical info out here for 700+ members to read -
you
> might want to check the accuracy of your statements first.
>
> Latr,
>
> Shane
>
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 11:50:36 EDT