Cam Diagrams?

jluetjen · jluetjen's Garage

Has anyone ever mapped out an S or a 906 cam? How about a GE80 or GE60? By "mapped out" I mean one of those cam charts with the two humps showing the lift on the Y axis and the crank angle on the X axis.

jgparker · jgparker's Garage

I mapped an S-cam a while ago. I did a CIS cam too, but nobody wants to see that. Here is a picture. Let me know if you want the excel file. This is actually the profile of a Web-cam grind.

camgrinder · 07-05-2004, 04:45 PM

JGParker has a valve lift vs. crank angle graph. I can also do valve acceleration vs. crank angle and Velocity vs. crank angles and others.
Computers are great....

We adapted a "Cam Doctor" to a cylinder head and cam carrier.
The Cam Dr. has 2 encoders, a rotory and a linear. Just pop a cam in, adjust the valves and spin it up. Saves it to a .c1 file which is read by various software programs.
Saves a lot of time (hours) over hand plotting a camshaft.

Mark McClure · 07-05-2004, 05:15 PM

Since the rocker arm is not a 1:1 relationship, does measuring the valve lift need to be recalculated to give the true profile or are all profiles measured the same and therefore the equalion is the same.

The reason for the questionis that I thought that "cam doctors" measured cam lobes.

Cheers

Mark...........

camgrinder · 07-05-2004, 05:46 PM

The 911 rocker arm is variable ratio. Since the contact point sweeps across the face of the rocker, moving from a close point in relation to the pivot to the furthest away the ratio changes. the valve lift curve is symetrical while the cam lobe shape is not.
The average ratio at full lift is 1.47-1. Calculating full lift at the cam lobe to full lift at the valve.
Measuring 911 cams at the valve is the best way. And the best way to compare cam to cam.

We check more than one type of camshaft at the valve. With a radius rocker, or roller rocker where the roller contacts the camshaft lobe (Ford 4.6 V8) it is the only way to know what the engine truely sees.

Mark McClure · 07-05-2004, 09:34 PM

OK..........that explains a lot! especially the variable point on the rocker pad. Never though of that. It makes sence to measure under the same conditions ie at the valve for each profile! I was under the beliefe that the "cam Doctor" could be used on any cam and did not use a valave rocker setup to profile the cam.

Cheers

Mark.

camgrinder · 07-06-2004, 04:42 PM

This first graph is for a GE-80 cam

This next is for a 3.8 RSR factory cam

This one is a new cam 318/290-106

jluetjen · jluetjen's Garage

Thanks John!
Any chance that you can share the numaric data, velocity and acceleration numbers too? (If that data for the "new cam" is confidential, that's OK too). That was exactly the information that I was trying to get to.

Thanks for sharing!
- John

Jeff Alton · 07-06-2004, 07:53 PM

John, what application is that new cam (318/290-106) used in??

Thanks, Jeff

camgrinder · 07-06-2004, 08:26 PM

It is used for all out racing only. Its not a drop in deal at all.

It is in between our 314/296-104 and the 324/304-100
And it has a lot more valve lift .558"/.490"
.
We have made it for 50mm Pmo 3.4 litres, and some 3.8 litres with TWM throttle bodies. So far with excellent results, but no long term feedback yet.

racing97 · 07-07-2004, 06:55 AM

I noticed in the graphs camgrinder was kind enough to post, that at the
lash ramp into the
constant acceleration stage and also on the closing side of all but one of the graphs quite a poly-dyne type correction in the slope. Is that a function of testing (Cam Dr.) with a great deal of lash or by design?
Best regards

camgrinder · 02:23 PM

All three graphs are without zero lash. Yes the designs are not all the same style. Even intake to exhaust profiles have different ramps.

jgparker · jgparker's Garage

Just out of curiousity, why do the intake lobes seem to have longer slower ramps than the exhaust?

Thanks,

JP

camgrinder · 07-07-2004, 07:06 PM

Here is a plot of the Velocity and accelerations.
This is a GT-II cam

camgrinder · 07:18 PM

The intake ramp has higher acceleration than the exhaust. With the valve lift curve alone it is hard to see.

JgParker, I am guessing your plot was done with valve lash of .004"/.006" ?

In case anyone is confused to which is the Intake and which is the Exhaust. The exhaust is the red line on the left side and the intake the dark blue line on the right.

jluetjen · jluetjen's Garage

John; you lost me.

Are the acceleration and velocity numbers that you posted for a different cam then you displayed data for earlier? Or is GT-II another name for one of the cams posted earlier?

jgparker · jgparker's Garage

yup, I did my profile measuring the lift on the valves with 0.1mm lash. I was trying to accuratly measure the real-world valve lift in the application. Here is how I did it, for anyone who missed the original post:

This is no cam doctor, but It does work.

JP

camgrinder · 07-08-2004, 02:20 PM

The GT-II plots are not the same as the earlier postings. Just some I had in a file to show what the curves look like.

911sTarga · 07-12-2005, 02:51 PM

Quote:

Originally posted by jgparker
[B]I mapped an S-cam a while ago. I did a CIS cam too, but nobody wants to see that.

Actually, I would!

I'm looking for this exact info right now! I'd like the open/closing points, lift, duration, LSA, etc... for both cams.

Any info would be greatly appreciated!

Thanks!

Jay

jgparker · jgparker's Garage

Jay,

I sent the cam profile file to your email. I think jluetjen has collected a lot of profiles too, so you may want to check with him too. I hope this is helpfull.

Good luck,

Jonathan
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