[Z06] 1.7 rockers v. 1.8 rockers math. Tech savvy please comment.
#1
Melting Slicks
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1.7 rockers v. 1.8 rockers math. Tech savvy please comment.
I decided awhile ago to pull my heads and upgrade them to mitigate the whole exhaust valve issue. The sticking point for me has been the cam. I've been trying to decide on and off for months and I've gotten close but ran into tech issue recently and wanted to run it past some of you more experienced modders/ builders.
The Z06 has 1.8 rockers and as such when picking a cam it's important to identify one designed for 1.8 rockers. That way the lift numbers published for the cam represent what the application will experience.
Now if I were to find a cam that is designed for a 1.7 rocker setup what exactly is the impact? In other words how are the lift numbers affected when using a cam designed for 1.7 rockers in a car with 1.8 rockers?
I've done some research and wanted to know if my conclusions are correct.
Here is the scenario:
The cam has published lift numbers of .610/ .620 with 1.7 rockers.
If I were to run this with 1.8 rockers I can do some math and find out what the revised lift numbers are. The equation I found is very simple.
(lift/1.7)1.8 so (.610/1.7)1.8 = .6458 or .650 lift
(.620/1.7)1.8 = .6564 or .660 lift
Am I correct? Is this equation correct? The published lift numbers are well within the range I'm looking at for my application but if the rockers raise lift as indicated then I should steer clear of this cam since I want to stay at or below .640. Unless of course I change the rockers out for 1.7's.
Comments welcome.
The Z06 has 1.8 rockers and as such when picking a cam it's important to identify one designed for 1.8 rockers. That way the lift numbers published for the cam represent what the application will experience.
Now if I were to find a cam that is designed for a 1.7 rocker setup what exactly is the impact? In other words how are the lift numbers affected when using a cam designed for 1.7 rockers in a car with 1.8 rockers?
I've done some research and wanted to know if my conclusions are correct.
Here is the scenario:
The cam has published lift numbers of .610/ .620 with 1.7 rockers.
If I were to run this with 1.8 rockers I can do some math and find out what the revised lift numbers are. The equation I found is very simple.
(lift/1.7)1.8 so (.610/1.7)1.8 = .6458 or .650 lift
(.620/1.7)1.8 = .6564 or .660 lift
Am I correct? Is this equation correct? The published lift numbers are well within the range I'm looking at for my application but if the rockers raise lift as indicated then I should steer clear of this cam since I want to stay at or below .640. Unless of course I change the rockers out for 1.7's.
Comments welcome.
#2
Drifting
Yes your math is correct. another way is to look at the cam card and it will give you lobe lift, multiply the lobe lift times 1.8
#3
Melting Slicks
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Thanks for the quick reply. Is it possible or even worth it to grind the cam down to maintain the 1.7 lift numbers with the 1.8 setup. When I type that out it sounds like a bad idea.
#4
Burning Brakes
that's just more work and more complicated than it needs to be, especially since you'll have to shim the valve lash due to grinding the cam.
#5
Le Mans Master
sounds like a disaster waiting to happen - instead, get a custom grind to what you want
#6
Drifting
#7
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I decided awhile ago to pull my heads and upgrade them to mitigate the whole exhaust valve issue. The sticking point for me has been the cam. I've been trying to decide on and off for months and I've gotten close but ran into tech issue recently and wanted to run it past some of you more experienced modders/ builders.
The Z06 has 1.8 rockers and as such when picking a cam it's important to identify one designed for 1.8 rockers. That way the lift numbers published for the cam represent what the application will experience.
Now if I were to find a cam that is designed for a 1.7 rocker setup what exactly is the impact? In other words how are the lift numbers affected when using a cam designed for 1.7 rockers in a car with 1.8 rockers?
I've done some research and wanted to know if my conclusions are correct.
Here is the scenario:
The cam has published lift numbers of .610/ .620 with 1.7 rockers.
If I were to run this with 1.8 rockers I can do some math and find out what the revised lift numbers are. The equation I found is very simple.
(lift/1.7)1.8 so (.610/1.7)1.8 = .6458 or .650 lift
(.620/1.7)1.8 = .6564 or .660 lift
Am I correct? Is this equation correct? The published lift numbers are well within the range I'm looking at for my application but if the rockers raise lift as indicated then I should steer clear of this cam since I want to stay at or below .640. Unless of course I change the rockers out for 1.7's.
Comments welcome.
The Z06 has 1.8 rockers and as such when picking a cam it's important to identify one designed for 1.8 rockers. That way the lift numbers published for the cam represent what the application will experience.
Now if I were to find a cam that is designed for a 1.7 rocker setup what exactly is the impact? In other words how are the lift numbers affected when using a cam designed for 1.7 rockers in a car with 1.8 rockers?
I've done some research and wanted to know if my conclusions are correct.
Here is the scenario:
The cam has published lift numbers of .610/ .620 with 1.7 rockers.
If I were to run this with 1.8 rockers I can do some math and find out what the revised lift numbers are. The equation I found is very simple.
(lift/1.7)1.8 so (.610/1.7)1.8 = .6458 or .650 lift
(.620/1.7)1.8 = .6564 or .660 lift
Am I correct? Is this equation correct? The published lift numbers are well within the range I'm looking at for my application but if the rockers raise lift as indicated then I should steer clear of this cam since I want to stay at or below .640. Unless of course I change the rockers out for 1.7's.
Comments welcome.
#8
Melting Slicks
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Thanks for the feedback guys. I've learned how to calculate lift if applying a 1.7 rocker cam in a 1.8 application and I've learned to make sure I spec a cam designed for a 1.8 rocker set up.