Solving the HKS 272 Cam Timing Mystery
Originally Posted by Ted B
No, you did it right. Cam gear marks = cam degrees, and -4/-1 is a CAM DEGREE setting!!
So when you set -4intake .. you dial the cam gear markings to 2 marks ( = 4 crank degree on mine) or you go 4 marks (= 8 crank degrees) ?!?!?!
Before you stir the water .. it was clear .. now it's just plain muddy !!!
Originally Posted by gunzo
Alright .. really confused now !!
So when you set -4intake .. you dial the cam gear markings to 2 marks ( = 4 crank degree on mine) or you go 4 marks (= 8 crank degrees) ?!?!?!
Before you stir the water .. it was clear .. now it's just plain muddy !!!
So when you set -4intake .. you dial the cam gear markings to 2 marks ( = 4 crank degree on mine) or you go 4 marks (= 8 crank degrees) ?!?!?!
Before you stir the water .. it was clear .. now it's just plain muddy !!!
For the "-4/-1" setting that people talk about, you set your adjustable cam GEARS to - 4 marks and -1 mark.
l8r)
Ok, maybe this will clear the muddy water...
As installed straight up, the HKS 272 cams are ground on 110deg LC and have a LSA of 110deg.
If a -4/-1 setting is desired, we look at our cam gear marks and adjust the Intake cam to 4 deg retard and retard the exhaust cam 1 deg.
The -4/-1 setting is represented in cam gears, let's see what this does to our cam specs:
The intake cam has a LC of 110 deg. If we retard the intake cam 4 cam degrees, this equals 8 crank degrees. The new setting gives the intake cam an LC of 118 deg because retarding the intake cam INCREASES its LC.
The exhaust cam has a LC of 110 deg. If we retard the intake cam 1 cam degrees, this equals 2 crank degrees. The new setting gives the intake cam an LC of 108 deg because retarding the exhaust cam REDUCES its LC.
Since LSA = (Intake LC + Exhaust LC)/2, the new LSA = 117deg.
Notes:
- Remember, the EXHAUST lobe comes around just before the INTAKE lobe, not the other way around. As the exhaust lobe comes around, the exhaust gases are vented, then you have overlap when the intake valve opens immediately afterward, followed by the long blank section between the lobes is where the cam is turning during the compression stroke, when no valves are open.
- LSA is always expressed in CAM degrees because it tells you the angle of separation between the intake and exhaust LOBES on the cam itself.
- Lobe centers are always expressed in CRANK degrees because they tell you the position of the crankshaft with respect to the cam lobes.
As installed straight up, the HKS 272 cams are ground on 110deg LC and have a LSA of 110deg.
If a -4/-1 setting is desired, we look at our cam gear marks and adjust the Intake cam to 4 deg retard and retard the exhaust cam 1 deg.
The -4/-1 setting is represented in cam gears, let's see what this does to our cam specs:
The intake cam has a LC of 110 deg. If we retard the intake cam 4 cam degrees, this equals 8 crank degrees. The new setting gives the intake cam an LC of 118 deg because retarding the intake cam INCREASES its LC.
The exhaust cam has a LC of 110 deg. If we retard the intake cam 1 cam degrees, this equals 2 crank degrees. The new setting gives the intake cam an LC of 108 deg because retarding the exhaust cam REDUCES its LC.
Since LSA = (Intake LC + Exhaust LC)/2, the new LSA = 117deg.
Notes:
- Remember, the EXHAUST lobe comes around just before the INTAKE lobe, not the other way around. As the exhaust lobe comes around, the exhaust gases are vented, then you have overlap when the intake valve opens immediately afterward, followed by the long blank section between the lobes is where the cam is turning during the compression stroke, when no valves are open.
- LSA is always expressed in CAM degrees because it tells you the angle of separation between the intake and exhaust LOBES on the cam itself.
- Lobe centers are always expressed in CRANK degrees because they tell you the position of the crankshaft with respect to the cam lobes.
Last edited by Ted B; Apr 1, 2005 at 07:20 AM.
The 264 exhaust cam has several degrees less of effective duration as compared to the 272 cam. I would not use a wide lobe center setting (e.g. -4/-1) with that cam set. Where you'd set your cams varies with what you want to gain and what you're willing to give in return.
There's some good info on AMS' website as well for learning cam basix: http://www.automotosports.com/magazine_articles2.asp
l8r)
l8r)
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From: Owner - TSR 954-275-3414 Hollywood, Florida
Originally Posted by Ted B
The 264 exhaust cam has several degrees less of effective duration as compared to the 272 cam. I would not use a wide lobe center setting (e.g. -4/-1) with that cam set. Where you'd set your cams varies with what you want to gain and what you're willing to give in return.
Thanks, I'll try the -3/-3.
It's Dr.Mr. I'm just posting from my tuner's shop.
Originally Posted by Ted B
Ok, maybe this will clear the muddy water...
As installed straight up, the HKS 272 cams are ground on 110deg LC and have a LSA of 110deg.
If a -4/-1 setting is desired, we look at our cam gear marks and adjust the Intake cam to 4 deg retard and retard the exhaust cam 1 deg.
The -4/-1 setting is represented in cam gears, let's see what this does to our cam specs:
The intake cam has a LC of 110 deg. If we retard the intake cam 4 cam degrees, this equals 8 crank degrees. The new setting gives the intake cam an LC of 118 deg because retarding the intake cam INCREASES its LC.
The exhaust cam has a LC of 110 deg. If we retard the intake cam 1 cam degrees, this equals 2 crank degrees. The new setting gives the intake cam an LC of 108 deg because retarding the exhaust cam REDUCES its LC.
Since LSA = (Intake LC + Exhaust LC)/2, the new LSA = 117deg.
Notes:
- Remember, the EXHAUST lobe comes around just before the INTAKE lobe, not the other way around. As the exhaust lobe comes around, the exhaust gases are vented, then you have overlap when the intake valve opens immediately afterward, followed by the long blank section between the lobes is where the cam is turning during the compression stroke, when no valves are open.
- LSA is always expressed in CAM degrees because it tells you the angle of separation between the intake and exhaust LOBES on the cam itself.
- Lobe centers are always expressed in CRANK degrees because they tell you the position of the crankshaft with respect to the cam lobes.
As installed straight up, the HKS 272 cams are ground on 110deg LC and have a LSA of 110deg.
If a -4/-1 setting is desired, we look at our cam gear marks and adjust the Intake cam to 4 deg retard and retard the exhaust cam 1 deg.
The -4/-1 setting is represented in cam gears, let's see what this does to our cam specs:
The intake cam has a LC of 110 deg. If we retard the intake cam 4 cam degrees, this equals 8 crank degrees. The new setting gives the intake cam an LC of 118 deg because retarding the intake cam INCREASES its LC.
The exhaust cam has a LC of 110 deg. If we retard the intake cam 1 cam degrees, this equals 2 crank degrees. The new setting gives the intake cam an LC of 108 deg because retarding the exhaust cam REDUCES its LC.
Since LSA = (Intake LC + Exhaust LC)/2, the new LSA = 117deg.
Notes:
- Remember, the EXHAUST lobe comes around just before the INTAKE lobe, not the other way around. As the exhaust lobe comes around, the exhaust gases are vented, then you have overlap when the intake valve opens immediately afterward, followed by the long blank section between the lobes is where the cam is turning during the compression stroke, when no valves are open.
- LSA is always expressed in CAM degrees because it tells you the angle of separation between the intake and exhaust LOBES on the cam itself.
- Lobe centers are always expressed in CRANK degrees because they tell you the position of the crankshaft with respect to the cam lobes.
So all these while I've been setting -2/-0.5 CAM GEAR degree setting while quoting -4/-1 CRANK degree !!
Thanks for the clarifications ..
Went ahead and tried the 'NEW DEGREEs' ..
Hated -4/-1 almost 0 spool up until 4000 (necksnapping feeling) about 3-5psi behind -2/-0.5 setting
now testing +2/+2 .. liking it right now .. pulls much better from 3k rpms onwards .. maybe abit more higher end also .. gotta check the log later for the acceleration rates
Originally Posted by Ludikraut
There's some good info on AMS' website as well for learning cam basix: http://www.automotosports.com/magazine_articles2.asp
l8r)
l8r)
But the Mag articles are GREAT !!!
Originally Posted by Ted B
Ok, maybe this will clear the muddy water...
As installed straight up, the HKS 272 cams are ground on 110deg LC and have a LSA of 110deg.
If a -4/-1 setting is desired, we look at our cam gear marks and adjust the Intake cam to 4 deg retard and retard the exhaust cam 1 deg.
The -4/-1 setting is represented in cam gears, let's see what this does to our cam specs:
The intake cam has a LC of 110 deg. If we retard the intake cam 4 cam degrees, this equals 8 crank degrees. The new setting gives the intake cam an LC of 118 deg because retarding the intake cam INCREASES its LC.
The exhaust cam has a LC of 110 deg. If we retard the intake cam 1 cam degrees, this equals 2 crank degrees. The new setting gives the intake cam an LC of 108 deg because retarding the exhaust cam REDUCES its LC.
Since LSA = (Intake LC + Exhaust LC)/2, the new LSA = 117deg.
Notes:
- Remember, the EXHAUST lobe comes around just before the INTAKE lobe, not the other way around. As the exhaust lobe comes around, the exhaust gases are vented, then you have overlap when the intake valve opens immediately afterward, followed by the long blank section between the lobes is where the cam is turning during the compression stroke, when no valves are open.
- LSA is always expressed in CAM degrees because it tells you the angle of separation between the intake and exhaust LOBES on the cam itself.
- Lobe centers are always expressed in CRANK degrees because they tell you the position of the crankshaft with respect to the cam lobes.
As installed straight up, the HKS 272 cams are ground on 110deg LC and have a LSA of 110deg.
If a -4/-1 setting is desired, we look at our cam gear marks and adjust the Intake cam to 4 deg retard and retard the exhaust cam 1 deg.
The -4/-1 setting is represented in cam gears, let's see what this does to our cam specs:
The intake cam has a LC of 110 deg. If we retard the intake cam 4 cam degrees, this equals 8 crank degrees. The new setting gives the intake cam an LC of 118 deg because retarding the intake cam INCREASES its LC.
The exhaust cam has a LC of 110 deg. If we retard the intake cam 1 cam degrees, this equals 2 crank degrees. The new setting gives the intake cam an LC of 108 deg because retarding the exhaust cam REDUCES its LC.
Since LSA = (Intake LC + Exhaust LC)/2, the new LSA = 117deg.
Notes:
- Remember, the EXHAUST lobe comes around just before the INTAKE lobe, not the other way around. As the exhaust lobe comes around, the exhaust gases are vented, then you have overlap when the intake valve opens immediately afterward, followed by the long blank section between the lobes is where the cam is turning during the compression stroke, when no valves are open.
- LSA is always expressed in CAM degrees because it tells you the angle of separation between the intake and exhaust LOBES on the cam itself.
- Lobe centers are always expressed in CRANK degrees because they tell you the position of the crankshaft with respect to the cam lobes.
this link is not making it easier...
http://www.nightrider.com/biketech/camlsatable.htm
Last edited by Jorge T; Apr 4, 2005 at 07:48 PM.