Re: Cam tuning

[Shannen Durphey <shannen@grolen.com>]

Scott Knight wrote:
> 
> Shannen Durphey wrote:
> >
> > Well, today I was replacing one of those same optisparks, and I
> 
> Heh.  All too common...
Yes, definitely.

  The sensor voltage goes from 0 to 5v when a leading
> edge comes up.  Does an ECM care when the voltage goes low again?
The time between pulses is used to determine rpm.  The uneven pulse
spacing will cause incorrect calculations.
> 
> There is one more fun fact.  The OBD-II LTx engines have a CPS
> (crankshaft position sensor) integrated right into the front cover as
> well...might even be the same pickup and reluctor wheel as the Vortec.
> Would be interesting to find out, since I have the new LTx pieces here
> in my office.  This is what I am going to use to trigger the Speed Pro
> controller on my LT1.  I could have just used the low-res side of the
> Opti, but I rather prefer a real crank sensor than one that is subject
> to timing chain quirks.  Especially since the newer LTx engines have
> such a nice one already available.

I had completely forgotten that.  The vortec timing cover is not
compatible with the LT1 engine, but the "disc" could be, so this is
the way to go.

> 
> You bring up a good point though.  The Vortec pieces would be great to
> use on a traditional SBC instead of a distributor or external trigger.
> Anywhere I can see pictures?
There were some on the gm high performance parts site.
http://www.spoperformanceparts.com/

Shannen

> --
> Scott Knight  mailto:scott@scottknight.com
> http://www.scottknight.com/ IRC:SS396man
> '95 Black Impala SS
> '94 Ducati 900SS CR
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