[Shotimes] New +20 cam dyno results

[Leigh Smith]

Alan;
All the prior cam tuning tips still apply.
The only diff being, you could increase the overlap, (decrease the lobe
center) to help blow off a little cylinder pressure if needed to decrease
the ping situation. The other tip is to be very careful with max timing when
you are ping or gas limited.
My Z28 had 11-1/2:1 with iron heads and was still capable of being tuned to
run on 93 octane. But it did like 97+ octane better! But the 2 octanes
required 2 diff timing curves. Lots of experimenting with both setups.
Lee


----- Original Message ----- 
From: "Alan Fanning" <Awfanning@earthlink.net>
To: "Leigh Smith" <leighsm@comcast.net>; "SHOtimes"
<shotimes@autox.team.net>
Sent: Monday, May 30, 2005 5:27 PM
Subject: Re: [Shotimes] New +20 cam dyno results


> So, since I have the "old school" Stage 1 cams in a SHO Shop 3.2l
> high-compression block, how does this relate to my situation - if at all?
I
> can't tolerate anything that increases the propensity to ping, for sure,
> since I'm limited to 91 octane gas here in CA.
>
>     Alan
>
>
> wrote:
>
> > Alan;
> > A recommended procedure would be to adjust the overlap / lobe center on
a
> > dyno to get the best peak torque, probably wider than stock w/ a +.020
cam.
> > Then the overall advance / retard could be done on the street / drags /
race
> > track under actual conditions. Some type of tuning tool like chrondikes,
> > stopwatch, or g-meter is needed. In most cases you will find advanced
cams,
> > to be actaully faster, regardless of the actual dyno curve / peak HP,
cause
> > they shift the hump in the torque curve lower. Maybe in Marks case where
he
> > is above 5k all the time, retarded cams would be faster. I had gotten
some
> > cam recommendations from one of the best cam tuners at Cam Dynamics (for
> > another application), and he recommended a lot of duration, with a wider
> > lobe center, for a higher & wider hp/torque curve. In his words it would
run
> > harder and rev higher for the best of both worlds. Very streetable and
very
> > fast. Drag racing currently favors just the opposite, with tight lobe
> > centers, cause it does make the peak slightly higher, but it also makes
the
> > power band very narrow, which is OK on a drag car, but not a street car,
or
> > a low cubic inch car like ours. Chevy numbers say maybe a 6 hp
difference at
> > peak out of 400, tight vs wide LC.
> > ..
> > I'm not sure what the SHO cam specs are, but with adjustable sprockets,
on
> > the +.020, I'd test it first by opening the lobe center up 4 degrees,
then
> > advancing everything 4 degrees. At that point point it should idle more
like
> > stock.
> > FWIW
> > Lee
> > (My Z28 street cam had 255 duration at .050, with a custom wide 116
degree
> > lobe center. 20-30 degrees more than a stock street cam, and 4-8 more
lobe
> > center, but that 350 reved to 7300 rpm vs 6000. And it still ran faster
> > retarded 4-6).
> > I'd even be interested in working with somebody to tame the +.040 cams
for
> > the street! Anybody interested? Ian? I could see a 7000-7300 power peak
with
> > an 8000 redline! And we should be able to tune the torque back in.
> >
> > ----- Original Message -----
> > From: "Alan Fanning" <Awfanning@earthlink.net>
> > To: "SHOtimes" <shotimes@autox.team.net>
> > Sent: Sunday, May 29, 2005 3:19 PM
> > Subject: Re: [Shotimes] New +20 cam dyno results