adjusting cams was Re: [Shotimes] Help with engine stumble in 95 MTX

[Ron Porter]

No!!

If you advance exhaust cams, the overlap increases!!

Advancing the intake cams will decrease overlap.

Without explaining it all here, draw yourself a diagram of how intake &
exhaust valves work during a complete crank cycle.

Ron Porter

-----Original Message-----
From: shotimes-admin@autox.team.net [mailto:shotimes-admin@autox.team.net]
On Behalf Of Ian Fisher
Sent: Wednesday, August 10, 2005 3:28 PM
To: Zach Leahy; George Fourchy
Cc: shotimes@autox.team.net
Subject: adjusting cams was Re: [Shotimes] Help with engine stumble in 95
MTX

Interestingly enough, a lot of people I have spoken to
have (or plan on) retarding their exhaust cams 3
degrees to dial out overlap when using reground cams.

On the other hand, Lance Cheney has his exhaust cam
advanced 3 degrees to dial out overlap. Technically,
this seems to make more sense, right?

Intake valves open first followed by the exhaust. If
the exhaust cams are advanced 3 degrees, they'll close
sooner and spend less time open while the intake
valves are open. Does this make sense?

I am not going to install my +20's straight up. I plan
on either advancing or retarding them 3 degrees to
start with. I just need to figure out which way to go.
I know that at 0 degrees of adjustment, there is too
much overlap so I'm not even going to bother with that
setting.

Ian
--- Zach Leahy <leahyz@gmail.com> wrote:

> Yes George, that's what I did, in a couple
> positions.  What the
> previous post was saying is that you are retarding
> or advancing the
> entire valvetrain, intake and exhause when you move
> one tooth on the
> belt.
> 
> To actually be able to change just the intake, you
> need to move the
> intake one way nad then correspondingly move the
> exhaust (chains) the
> other way.  That would allow you to adavance the
> inake perhaps and
> retard the exhaust, decreasing overlap, or opposite
> to add overlap, or
> advande everything forward, or back.  Becasue the
> intake and exhaust
> cam are chaned together in order to change just the
> intake, one needs
> to adjust 4 sprockets.
> 
> Z
> 
> On 8/10/05, George Fourchy <krazgeo@comcast.net>
> wrote:
> > On Wed, 10 Aug 2005 08:58:39 -0700 (PDT), Ian
> Fisher wrote:
> > 
> > >On the SHO, the intake cams can only be adjusted
> > >independently using adjustable sprockets such as
> > >Josh's timing chain sprockets.
> > 
> > Theoretically, if someone wanted to spend a bunch
> of money to buy those sprockets, I
> > suppose one could.
> > 
> > But if you divide the number of teeth in the
> factory sprockets by 360, you'll get
> > the number of degrees either side of TDC one tooth
> will give.  I don't have any
> > right here...they are in storage, but if there
> were 90 teeth, each one would be 4
> > degrees.  If there were 60 (probably closer to
> correct), then each would be 6
> > degrees.  If the crank sprocket has 30, then each
> one would be 12, probably a bit
> > much for a slight valve timing exercise.
> > 
> > ...that sounds about right....30 teeth on the
> small sprocket, and twice as much for
> > half the speed...60 on the bigger sprocket.....
> > 
> > Count the teeth, then adjust the cam sprockets by
> as many degrees as you want to
> > try.
> > 
> > George
> > _______________________________________________
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> > Shotimes@autox.team.net
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