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Super Moderator
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8,495 Posts
Discussion Starter #1 (Edited by Moderator)
First Id point out that nearly everyone occasionally confuses or at least makes the mistake of using the wrong abbreviation, (LSA, and LCA) these are terms,that are almost, at least in many discussions interchangeable. which they are not.
LSA =LOBE SEPARATION ANGLE ........LSA is ground into the cam during manufactured, and can,t change,


LOBE SEPARATION ANGLE
Above 114 Deg. = Extremely Wide
114-112 Deg. = Wide
112-110 Deg. = Moderately Wide
110-108 Deg. = Moderate
108-106 Deg. = Moderately Tight
106-104 Deg. = Tight
Below 104 Deg. = Extremely Tight

VARYING LOBE SEPARATION ANGLE
Tighten.................................................Widen
Moves Torque to Lower RPM.................Raise Torque to Higher RPM
Increases Maximum Torque..................Reduces Maximum Torque
Narrow Power Band..............................Broadens Power Band
Builds Higher Cylinder Pressure............Reduce Maximum Cylinder Pressure
Increase Chance of Engine Knock.........Decrease Chance of Engine Knock.
Increase Cranking Compression...........Decrease Cranking Compression
Increase Effective Compression............Decrease Effective Compression
Idle Vacuum is Reduced........................Idle Vacuum is Increased
Idle Quality Suffers...............................Idle Quality Improves
Open Valve-Overlap Increases.............Open Valve-Overlap Decreases
Closed Valve-Overlap Increases...........Closed Valve-Overlap Decreases
Natural EGR Effect Increases................Natural EGR Effect is Reduced
Decreases Piston-to-Valve Clearance...Increases Piston-to-Valve Clearance
LCA =(LOBE CENTER ANGLES)remember lobe center angles can be changed thru indexing the cam when degreeing it in
ADVANCING / RETARDING CAM TIMING

KEEP IN MIND MANY CAMS ARE FACTORY SET UP TO BE 4 DEGREES ADVANCED if INSTALLED DOT-TO-DOT

ADVANCING.
Begins Intake Event Sooner........................
Open Intake Valve Sooner..........................
Builds More Low-End Torque.......................
Decrease Piston-Intake Valve Clearance....
Increase Piston-Exhaust Valve Clearance...

RETARDING
Delays Intake Event Closes Intake
Keeps Intake Valve Open Later
Builds More High-End Power
Increase Piston-Intake Valve Clearance
Decrease Piston-Exhaust Valve Clearance











http://forum.grumpysperformance.com/viewtopic.php?f=52&t=1070

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=480

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=2782&p=7215&hilit=+overlap#p7215

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=90

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=2782&p=7433&hilit=+overlap#p7433
 

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DC Pit Crew Boss
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4,165 Posts
That's some good reading. Thanks for clearing some stuff up :thumbsup:
 

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Super Moderator
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8,495 Posts
Discussion Starter #5
As always, excellent info Grump! I wonder how many "tuner shops" even degree the cams they install.:cheers:
Id bet a lot FEWER than you might think!
Ive asked questions that they HAD to know to degree in a cam and gotten THAT "deer in the headlight stare" several times, from the guy who claimed to have taken the time and charged for degreeing in the cam...Id bet many of them think degreeing in a cam means, installing the timing set DOT-TO-DOT


many businesses do as little as they can get bye with doing..
Ive had machine shops try and charge me for torque plate honing on blocks and found they don,t even OWN a torque plate for the type of engine

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=90

http://forum.grumpysperformance.com/viewtopic.php?f=51&t=588&p=4946&hilit=+honing#p4946
 

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12 Posts
I even have a torque plate for the Subaru WRX motors....and only used it once.

I see almost NO shops no matter how well known degree cams when installing. But then again, how many are run or staffed by old farts like us Paul. :cheers:
 
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