Re: 1.6 rockers intake side

[tom hecht <baddd65@xxxxxxxxx>]

thank you tom!
everything i have read about racer brown has said the
cams are designed to run with a 1.5/1.6 set-up.
including the rockers assemblies they sell.

back to my point a long time ago, the majority of cams
for mopar, use designs based on 1.5/1.5.

in my case ultradyne has told me the gain from a
1.5/1.6 would not be worth the added expense, since
these cams are designed to work with 1.5/1.5 rockers.

on the flip side, several engine builders in the twin
cities are saying they like the 1.5/1.6 set-up on big
blocks, one in particular is swearing by "cam
dynamics". and he has built some of the quickest 440's
in the area.

since i have been using ultradynes i have had no
problems, and i know a couple very fast guys who also
use them with 1.5/1.5 rockers.

i think to a degree don is right, cams may be as
personal as chevy or ford, you like what you like, and
if you change brands even the smallest problem becomes
big "anti-brand" selling points.


tom
65 satellite






--- Tom Watters <tomwatters@xxxxxxxxxxx> wrote:

>
> My Racer Brown cam came with a card that showed lift
> and duration at 1.5
> and 1.6.  The 1.6 gives you a higher lift and could
> cause valve
> clearance problems on a decked block with shaved
> heads.  But I didnt
> think the cam had to be designed for it, you just
> run it through a
> calculation and you can determine what the new lift
> is.  Using a basic
> ratio calculation assuming you know the lift for the
> cam at 1.5, isn't
> New Lift = (Current Lift * 1.6) / 1.5
> 
> On an engine being build for Torque and Power,
> Assuming no clearance
> problems, wouldnt a 1.6 ration rocker with a higher
> lift allow for more
> CFM to flow into the chamber?
> 
> Am I all wrong here?  Sensible?
> 
> --TOM
> 
> On Wed, 13 Jul 2005 08:39:59 -0400, "Don Dulmage"
> <big-d@xxxxxxxxxxxx>
> said:
> > 
> > Yes I know that trick it is often done on chevy
> SBs. 
> > We will give it  a whirl as well but my current
> belief is that the cam
> > was designed to take max advantage of the port
> design of the mopar head
> > and large lifters and it was designed for 1.5
> rockers . 
> > When we put 1.6s on we go a outside the cams
> carefully designed features
> > and it screws up the valve action and we lose
> power. I think that  to use
> > 1.6 rockers  the cam needs to be designed for
> them. I dont know if I said
> > it here before but we made a set of 1/7 s once
> from a set of crane iron
> > 1/5 adjustables (moved the adjusters inward about
> 30 years ago )  and the
> > results were not unlike the last test.(There was
> certainly no gain)
> > At the levels of cam we are running  which are
> relatively mild compard to
> > a pro stock cam etc  it would be no problem for
> the cam manufacture to
> > make a cam with the same figures and area under
> the curve with 1/5s that
> > would be the same as 1/6s are running on the 1/5
> cams we are using
> > currently. It is I think though true that cam
> timing is a very critical
> > thing and bolting on a set of 1.6s often hurts
> more than it helps. We
> > will keep flogging this though to find out for
> sure. I know for instance
> > putting 1/6s on a cam like the ST-H-42 Racer brown
> which is a FULL ON cam
> > with absolutley no compromises would almost
> certainly ruin its
> > performance as it is already maxed out. and you
> cant go beyond that with
> > out messing things up.
> > 1/6 while they do not change the duration from
> actual opening and closing
> > do change the "effective duration" at 050 and at
> .200 lift. because the
> > valve is open more earlier and flow events are
> changed.  Serious cam
> > manufacturuer give the duration at 200 " and at
> 050  for this reason. 
> > Because the valve would be at the 050 or .200 lift
> point earlier  the
> > duration at these points would be greater than it
> would with 1/5 rockers.
> > It takes very  few degrees to make or ruin cams
> performance 
> > . Anyway we will try several more combos and see
> if we ever get an
> > increase. (i AM BETTING NO)  
> > I have yet to see anyone running through the pits
> saying i put on 1/6s
> > and dropped 2 tenths. Usually they are very quiet 
> because they just
> > spent 3 or 4 hundred bucks and got nothing or an
> even worse result and
> > think they did something wrong. We often hear" it
> feels better" or "seem
> > a lot better" but if it aint on the time slip,
> baby , then it aint there. 
> > However i reserve the right to say "I was wrong"
> should I get positive
> > results. This is just my current thinking today.
> > Don 
> > Author of
> > Return to Deutschland (True Adventure)
> > Old Reliable (Mopar)
> > http://stores.ebay.ca/Don-Dulmage-Enterprises
> > [Non-text portions of this message have been
> removed]
> > 
> Tom
> 65 Dart GT 'vert
> 68 Plymouth 'vert
> Las Vegas, NV
> 
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