Cam degreeing questions
Cam degreeing questions The following specs are from a cam report:
Centerline 109.25
.05 Lift C/L 109.68
Duration @0.50 Intake 228.18 Exhaust 231.67
LSA 113.25
The cam has 4 degrees of advance.
readings from measurements of plus and minus 0.05” from max lift are
84 and 150
So (84 + 150) / 2 = 117
Should I advance or retard the cam from the centerline indicated on the report which is 109.68
or should I advance or retard the cam from the intake duration @ .05 and divide that by two: 228.18 / 2 approx 114 ?
When a cam has gound in advance, does it only advance the intake lobe?
Centerline 109.25
.05 Lift C/L 109.68
Duration @0.50 Intake 228.18 Exhaust 231.67
LSA 113.25
The cam has 4 degrees of advance.
readings from measurements of plus and minus 0.05” from max lift are
84 and 150
So (84 + 150) / 2 = 117
Should I advance or retard the cam from the centerline indicated on the report which is 109.68
or should I advance or retard the cam from the intake duration @ .05 and divide that by two: 228.18 / 2 approx 114 ?
When a cam has gound in advance, does it only advance the intake lobe?
The following instructions are why I am confused.
In Comp Cams “Camshaft Installation and Degreeing Procedure”, in step 12 it states “Reference back to your cam spec card and see what the recommended intake centerline is.”. But what is the recommended intake centerline, the intake duration at 0.05” divided by 2 or according to my report “.050 Lift C/L 109.68 ATDC”?
If you look at the COMP CAM card for the LGM G5X2 cam card referenced in this thread https://ls1tech.com/forums/generation-iii-internal-engine/327734-cam-guide.html the intake duration at .05 is 232 so of course half of that is 116. However it also states “THESE SPECS ARE FOR CAM INSTALLED AT 109.0 INTAKE CENTERLINE”. Perhaps they mean “THESE SPECS” are the duration numbers following the phrase I just quoted.
So is the recommended intake centerline for the LGM G5X2 cam 116 or 109?
In Comp Cams “Camshaft Installation and Degreeing Procedure”, in step 12 it states “Reference back to your cam spec card and see what the recommended intake centerline is.”. But what is the recommended intake centerline, the intake duration at 0.05” divided by 2 or according to my report “.050 Lift C/L 109.68 ATDC”?
If you look at the COMP CAM card for the LGM G5X2 cam card referenced in this thread https://ls1tech.com/forums/generation-iii-internal-engine/327734-cam-guide.html the intake duration at .05 is 232 so of course half of that is 116. However it also states “THESE SPECS ARE FOR CAM INSTALLED AT 109.0 INTAKE CENTERLINE”. Perhaps they mean “THESE SPECS” are the duration numbers following the phrase I just quoted.
So is the recommended intake centerline for the LGM G5X2 cam 116 or 109?
Last edited by squarehead; May 31, 2008 at 09:32 AM. Reason: editing
Here are the valve angles on the cam report.
Centerline 109.25 ATDC
.05 Lift C/L 109.68 ATDC
Duration @0.50 Intake 228.19 Exhaust 231.67
for Lift at 0.050 Dur 228.19 open 4.42 BTDC close 43.78 ABDC
The measurements I took were at 84 ATDC and 150 ATDC
Centerline 109.25 ATDC
.05 Lift C/L 109.68 ATDC
Duration @0.50 Intake 228.19 Exhaust 231.67
for Lift at 0.050 Dur 228.19 open 4.42 BTDC close 43.78 ABDC
The measurements I took were at 84 ATDC and 150 ATDC
The following specs are from a cam report:
Centerline 109.25
.05 Lift C/L 109.68
Duration @0.50 Intake 228.18 Exhaust 231.67
LSA 113.25
The cam has 4 degrees of advance.
readings from measurements of plus and minus 0.05” from max lift are
84 and 150
So (84 + 150) / 2 = 117
Should I advance or retard the cam from the centerline indicated on the report which is 109.68
or should I advance or retard the cam from the intake duration @ .05 and divide that by two: 228.18 / 2 approx 114 ?
When a cam has gound in advance, does it only advance the intake lobe?
Centerline 109.25
.05 Lift C/L 109.68
Duration @0.50 Intake 228.18 Exhaust 231.67
LSA 113.25
The cam has 4 degrees of advance.
readings from measurements of plus and minus 0.05” from max lift are
84 and 150
So (84 + 150) / 2 = 117
Should I advance or retard the cam from the centerline indicated on the report which is 109.68
or should I advance or retard the cam from the intake duration @ .05 and divide that by two: 228.18 / 2 approx 114 ?
When a cam has gound in advance, does it only advance the intake lobe?
Using the timing set, this also advances the exhaust as well which should be retarded the same 8 degrees as the intake.
This is a cam profile:
The left curve is the exhaust, the right is the intake, and the vertical line in the center is obviously TDC. If the centerline of the intake is 117 degrees away from TDC, and neds to be 109 degrees, then it needs to be brought back towards the left closer to TDC (or 0) reducing the distance between TDC and the centerline.
If the intake is 8 degrees too far away from TDC, then the exhaust centerline is going to be 8 degrees too close to TDC.
Moving the profiles to the left moves BOTH centerlines (intake closer, exhaust further) and makes BOTH valves open and close sooner, so thats why it is called advance.
Hope that helps a bit.
Kent
The following instructions are why I am confused.
In Comp Cams “Camshaft Installation and Degreeing Procedure”, in step 12 it states “Reference back to your cam spec card and see what the recommended intake centerline is.”. But what is the recommended intake centerline, the intake duration at 0.05” divided by 2 or according to my report “.050 Lift C/L 109.68 ATDC”?
If you look at the COMP CAM card for the LGM G5X2 cam card referenced in this thread https://ls1tech.com/forums/showthread.php?t=327734 the intake duration at .05 is 232 so of course half of that is 116. However it also states “THESE SPECS ARE FOR CAM INSTALLED AT 109.0 INTAKE CENTERLINE”. Perhaps they mean “THESE SPECS” are the duration numbers following the phrase I just quoted.
So is the recommended intake centerline 116 or 109?
In Comp Cams “Camshaft Installation and Degreeing Procedure”, in step 12 it states “Reference back to your cam spec card and see what the recommended intake centerline is.”. But what is the recommended intake centerline, the intake duration at 0.05” divided by 2 or according to my report “.050 Lift C/L 109.68 ATDC”?
If you look at the COMP CAM card for the LGM G5X2 cam card referenced in this thread https://ls1tech.com/forums/showthread.php?t=327734 the intake duration at .05 is 232 so of course half of that is 116. However it also states “THESE SPECS ARE FOR CAM INSTALLED AT 109.0 INTAKE CENTERLINE”. Perhaps they mean “THESE SPECS” are the duration numbers following the phrase I just quoted.
So is the recommended intake centerline 116 or 109?
Last edited by KCS; May 31, 2008 at 09:30 AM. Reason: typo
Are cam positions out of alignment as much as 8 degrees? It seems some adjustable sets do not adjust that much. On a side note this is an LS2, I just thought this was more of a generic question and there would be more visiblity in this section.
My cam has 4 degrees of advance ground in...so if you were using the 1/2 duration 228/2 - 4 degrees of advance it is close to the .050 Lift C/L of 109.68....so I'm wondering are the intake lobes just advanced with respect to the exhaust lobes?
btw I also believe the LGM G5X2 also has advance ground in which may explain the difference between the 1/2 duration number and the centerline.
My cam has 4 degrees of advance ground in...so if you were using the 1/2 duration 228/2 - 4 degrees of advance it is close to the .050 Lift C/L of 109.68....so I'm wondering are the intake lobes just advanced with respect to the exhaust lobes?
btw I also believe the LGM G5X2 also has advance ground in which may explain the difference between the 1/2 duration number and the centerline.
Last edited by squarehead; May 31, 2008 at 03:04 PM. Reason: spelling
Trending Topics
Pay more close to your valve events (IVO, EVC) and not so much about the centerlines. Centerlines can be OFF, but the IVO, IVC, EVO, EVC are still where they need to be and that's what you should pay more attention to IMO. Most cam lobes, atleast Cranes have offset ground into the lobes, and that can make the centerlines look off, but the VALVE EVENTS are exactly where they need to be. It doesn't hurt to have a little more advancement in the cam then you want, to take in place of HIGH RPM chain stretch.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Pay more close to your valve events (IVO, EVC) and not so much about the centerlines. Centerlines can be OFF, but the IVO, IVC, EVO, EVC are still where they need to be and that's what you should pay more attention to IMO. Most cam lobes, atleast Cranes have offset ground into the lobes, and that can make the centerlines look off, but the VALVE EVENTS are exactly where they need to be. It doesn't hurt to have a little more advancement in the cam then you want, to take in place of HIGH RPM chain stretch.
Below are the intake valve events at different lift points from the cam report.
LIFT DUR OPEN CLOSE AREA
0.006 279.91 29.61 BTDC 70.31 ABDC 29.38
0.02 255.39 17.82 BTDC 57.57 ABDC 29.24
0.05 228.19 5.52 BTDC 43.7 ABDC 28.79
0.1 199.26 9.89 ATDC 29.15 ABDC 27.62
0.15 176.01 21.42 ATDC 17.43 ABDC 26.27
0.2 153.34 32.7 ATDC 6.04 ABDC 24.09
0.25 128.8 44.94 ATDC 6.25 BBDC 21.52
0.3 99.8 59.5 ATDC 20.8 BBDC 17.2
0.35 58.85 79.84 ATDC 41.3 BBDC 10.47
How do I pay more attention or verify this?
Below are the intake valve events at different lift points from the cam report.
LIFT DUR OPEN CLOSE AREA
0.006 279.91 29.61 BTDC 70.31 ABDC 29.38
0.02 255.39 17.82 BTDC 57.57 ABDC 29.24
0.05 228.19 5.52 BTDC 43.7 ABDC 28.79
0.1 199.26 9.89 ATDC 29.15 ABDC 27.62
0.15 176.01 21.42 ATDC 17.43 ABDC 26.27
0.2 153.34 32.7 ATDC 6.04 ABDC 24.09
0.25 128.8 44.94 ATDC 6.25 BBDC 21.52
0.3 99.8 59.5 ATDC 20.8 BBDC 17.2
0.35 58.85 79.84 ATDC 41.3 BBDC 10.47
Below are the intake valve events at different lift points from the cam report.
LIFT DUR OPEN CLOSE AREA
0.006 279.91 29.61 BTDC 70.31 ABDC 29.38
0.02 255.39 17.82 BTDC 57.57 ABDC 29.24
0.05 228.19 5.52 BTDC 43.7 ABDC 28.79
0.1 199.26 9.89 ATDC 29.15 ABDC 27.62
0.15 176.01 21.42 ATDC 17.43 ABDC 26.27
0.2 153.34 32.7 ATDC 6.04 ABDC 24.09
0.25 128.8 44.94 ATDC 6.25 BBDC 21.52
0.3 99.8 59.5 ATDC 20.8 BBDC 17.2
0.35 58.85 79.84 ATDC 41.3 BBDC 10.47
I have been using Comp Cams directions along with a degree wheel and dial indicator. They recommend placing the dial on the spring retainer, so I divided the travel displayed on the indicator by 1.7 For me the 0.006 measurements are fairly difficult to take perhaps too much valvetrain slop. At any rate my readings are not close to the cam report.
I have been using Comp Cams directions along with a degree wheel and dial indicator. They recommend placing the dial on the spring retainer, so I divided the travel displayed on the indicator by 1.7 For me the 0.006 measurements are fairly difficult to take perhaps too much valvetrain slop. At any rate my readings are not close to the cam report.
That is good advice. I did try that once but once the lifter reached it max point it stuck up there I guess I have too much lube around that area.
Are cam positions out of alignment as much as 8 degrees? It seems some adjustable sets do not adjust that much. On a side note this is an LS2, I just thought this was more of a generic question and there would be more visiblity in this section.
My cam has 4 degrees of advance ground in...so if you were using the 1/2 duration 228/2 - 4 degrees of advance it is close to the .050 Lift C/L of 109.68....so I'm wondering are the intake lobes just advanced with respect to the exhaust lobes?
btw I also believe the LGM G5X2 also has advance ground in which may explain the difference between the 1/2 duration number and the centerline.
My cam has 4 degrees of advance ground in...so if you were using the 1/2 duration 228/2 - 4 degrees of advance it is close to the .050 Lift C/L of 109.68....so I'm wondering are the intake lobes just advanced with respect to the exhaust lobes?
btw I also believe the LGM G5X2 also has advance ground in which may explain the difference between the 1/2 duration number and the centerline.
Pay more close to your valve events (IVO, EVC) and not so much about the centerlines. Centerlines can be OFF, but the IVO, IVC, EVO, EVC are still where they need to be and that's what you should pay more attention to IMO. Most cam lobes, atleast Cranes have offset ground into the lobes, and that can make the centerlines look off, but the VALVE EVENTS are exactly where they need to be. It doesn't hurt to have a little more advancement in the cam then you want, to take in place of HIGH RPM chain stretch.
for lift at 0.100"
190.26/2 +9.89 = 109.52
the cam has 4 degrees of advance gound in
How do I pay more attention or verify this?
Below are the intake valve events at different lift points from the cam report.
LIFT DUR OPEN CLOSE AREA
0.05 228.19 5.52 BTDC 43.7 ABDC 28.79
_______________________________________________
I have been dividing the duration at 0.050 by 2 and adding to the opening event to arrive at the centerline....so 228.19/2 + (-4.42) = 109.675
for lift at 0.100"
190.26/2 +9.89 = 109.52
the cam has 4 degrees of advance ground in
Below are the intake valve events at different lift points from the cam report.
LIFT DUR OPEN CLOSE AREA
0.05 228.19 5.52 BTDC 43.7 ABDC 28.79
_______________________________________________
I have been dividing the duration at 0.050 by 2 and adding to the opening event to arrive at the centerline....so 228.19/2 + (-4.42) = 109.675
for lift at 0.100"
190.26/2 +9.89 = 109.52
the cam has 4 degrees of advance ground in
229.22/2 = 114.61 -5.52 = 109.09
I goofed, didn't correct for BTDC number after dividing in my prior post.
I am struggling on how you can be off by that much, 8 degrees.
Last edited by vettenuts; Jun 1, 2008 at 01:35 PM.