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<p>I never understood the advantage of 'twin' cams (assuming two
cams per bank of cylinders, one for intake and one for exhaust).
Can't the same results come from lobe profiles; i.e. one profile
for intake and one for exhaust, on the same cam? All the twin cam
setups I've seen have both cams driven by the same belt, so timing
will be the same for both cams. Is this idea just to have less
'load' for each cam?<br>
</p>
<p><br>
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<p>What does make sense to me is variable cam timing. My Mustang
accelerates smoothly and seamlessly, but on coasting deceleration
there is a noticeable 'bump' down in RPM around 1,800-2,000 RPM as
the ECU changes--advances?--the cam timing, but it only has one
cam per bank. I know the Honda VTEC engines have a third lobe,
that only comes into play at higher speeds (thanks Edd!).<br>
</p>
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<div class="moz-cite-prefix">On 7/8/2017 12:43 PM, David Porter
wrote:<br>
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<p>I guess my point in generating some "traffic" is best expressed
by Mr. Lawrence. With a single cam acting on the valve timing,
one can set it close to factory or deviate a couple degrees
advanced or retarded for low end torque or high rpm breathing.
It is still a trade off versus a twin cam head where both can be
affected and gains can be easily (?) obtained for both instances
he states. Not too sure we all have easy access to a dyno. These
old long stroke 6/4's were designed for grunt. That would be the
wise choice. They don't like to be spun up much, then the Welch
crank would be necessary. $$ dave<br>
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<div class="moz-cite-prefix">On 7/7/2017 7:16 PM, WILLIAM B
LAWRENCE wrote:<br>
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<p>According to Iskendarian You can optimize cam timing
either to provide a boost in low end torque by advancing
the timing by up to 8 degrees or in high end power by
retarding it a similar amount. </p>
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<p>Since I am looking for a low end boost and will rarely
exceed 3500 on the road I set mine 4 degrees in advance.</p>
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<p>Waiting to see how it works out...</p>
<p><br>
</p>
<p>Bill Lawrence</p>
<p>BN1 #554</p>
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