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Old 01-04-2011, 12:17 PM   #1
CAMAR0
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Join Date: Feb 2010
Location: Brick House
Posts: 645
LS7 Cam For Sale $100 + sh PRICE DROP + 4x 3 bolt cam sprocket for sale PICS ADDED!

I have a take out LS7 Cam that was pulled at 2,000 miles. Its a three bolt 4x cam that works with the newer LS motors. Its listed on Grrrr8 also hence the writing... same login if interested.. GM PN 12571251 PARTS ARE IN INDY, NOT AT THE CONDO IN FL

I was going to put this in my silverado but never got around to it. Also have the different cam sprocket for sale separately but I need to dig it out to see the part number.




Post on LS1Tech.com:
LS7 cam - 505 HP - 28 mpg
211 - intake duration @ .050
230 - exhaust duration @ .050
120 - LSA (lobe separation angle) camshaft degrees
120 - intake/exhaust lobe centerline straight up in crank degrees
123 - ILC (intake lobe centerline) factory installed @ 3 degrees retard
.591 - intake valve lift
.591 - exhaust valve lift

As opposed to a dual camshaft setup, a single cam's LSA will be fixed at birth, it cannot be altered. The ILC/ELC can be advanced or retarded with one affecting the other. Advancing the ILC, retards the ELC.......retarding the ILC, advances the ELC, but the 120 LSA relationship will never change or will the overlap.

The factory installs the LS7 in the 3 degree retarded position:
123 - ILC - (Intake Lobe Center)
117 - ELC - (Exhaust Lobe Center)
____________________

Quick overlap calc:

Add the in/ex duration
Divide by 4
Subtract the LSA
Multiply by 2

Example:

211 + 230 = 441
441 / by 4 = 110.25
110.25 - 120 = -9.75

-9.75 x 2 = -19.5
Overlap = -19.5 degrees of negative overlap
____________________

Wide SLA = low, zero or negative overlap for good gas milage and emmision control

Wide SLA = relatively early exhaust valve opening for restrictive exhaust systems

Wide SLA = relatively late intake valve closing for controlling dynamic pressure with 11:1 CR

Massive intake port flow capability allows relatively low 211 intake duration combined with .591 lift

Increased exhaust duration of 230, combined with early exhaust opening and .591 lift helps combat restrictive street exhaust system.
___________________

LS7 Cam profile @ ILC/ELC 120 straight up - 211/230 duration
IO......... -14.5 atdc
IC......... 45.5 abdc
EO......... 55 bbdc
EC......... -5 btdc

Overlap = -19.5 and 120 LSA
___________________

LS7 Cam profile @ ILC/ELC 123/117 - 3 degree retard - 211/230 duration
IO......... -17.5 atdc
IC......... 48.5 abdc
EO......... 52 bbdc
EC......... -2 btdc

Overlap = -19.5 and 120 LSA
__________________
Intake Timing calcs:
intake duration = 211
divide by 2 = 105.5
LSA = 120
subtract 120 from 105.5 = -14.5 IO
subtract -14.5 from 180 = 165.5
subtract 165.5 from 211 = 45.5 IC
Intake timing = IO -14.5 atdc --- IC 45.5 abdc
__________________
Exhaust Timing calcs:
exhaust duration = 230
divide by 2 = 115
LSA = 120
subtract 120 from 115 = -5 EC
subtract -5 from 180 = 175
subtract 175 from 230 = 55 EC
Exhaust timing = EO 55 bbdc --- EC -5 btdc
_________________
IO - -14.5 atdc
IC - 45.5 abdc
EO - 55 bbdc
EC - -5 btdc
_________________
To advance the cam, subtract the amount of advance in degrees from the intake and add to the exhaust.
To retard the cam, add the amount of retard in degrees to the intake and subtract from the exhaust.
Straight up 120 - ILC/120 - ELC
IO - -14.5 atdc
IC - 45.5 abdc
EO - 55 bbdc
EC - -5 btdc
Example: 3 degrees advance becomes 117 - ILC/223 - ELC
IO - -11.5 atdc
IC - 42.5 abdc
EO - 58 bbdc
EC - -8 btdc
________________
Straight up 120 - ILC/120 - ELC
IO - -14.5 atdc
IC - 45.5 abdc
EO - 55 bbdc
EC - -5 btdc
Example: 3 degrees retard becomes 223 - ILC/117 - ELC
IO - -17.5 atdc
IC - 48.5 abdc
EO - 52 bbdc
EC - -2 btdc

Last edited by CAMAR0; 01-04-2011 at 08:59 PM.
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