degreeing cams ... why?

[truckah]

i know that camshafts (through timing, lift, and duration) determine how much power you get and where it comes on in the rev range. i'm curious how you degree your cams to affect the desired result. any takers?

 

[first timer]

there are lots of talk about it, do a search for cam timing or degreeing

 

[RacingJake]

Moving the lobe centers toward each other is good for bottom end power and spreading the lobe centers farther apart is good for top end power. Some of us like to go past the 9K redline by a few thousand so guess which way we like to go ??

Advancing the intake closing number will cause an increase in compression too but go to far and you can have a piston to valve issue.

 

[posplayr]

These guys seem to have the best links

These guys seem to have the best links

Unlike a single camshaft care cam, since the GS has two separate cams, the relationship between intake, exhaust and crank can be adjusted separately.

http://www.compcams.com/Technical/TimingTutorial/

http://www.compcams.com/information/tutorials/

[FONT=Arial, Helvetica, sans-serif]The next point on the graph is the intake opening. This begins the overlap phase, which is very critical to vacuum, throttle response, emissions and especially, gas mileage. The amount of overlap, or the area between the intake opening and the exhaust closing, and where it occurs, is one of the most critical points in the engine cycle. If the intake valve opens too early, it will push the new charge into the intake manifold. If it occurs too late, it will lean out the cylinder and greatly hinder the performance of the engine. If the exhaust valve closes too early it will trap some of the spent gases in the combustion chamber, and if it closes too late it will over-scavenge the chamber; taking out too much of the charge, again creating an artificially lean condition. If the overlap phase occurs too early, it will create an overly rich condition in the exhaust port, severely hurting the gas mileage. So, as you can see, everything about overlap is critical to the performance of the engine.[/FONT]

http://www.circletrack.com/enginetech/ctrp_0805_camshaft_timing/lobe_lift_centerline.html


It is important enough that cars like the 1990 Q45 have electronic valve timing.

 

[jknappsax]

Never mind!

 

[reddirtrider]

Truckah, that's a great quote! And I've never had any luck explaining this to my anti-gun acquaintences. But it's good to see that somebody out there understands the intent of the Founding Fathers!

The second amendment isn't about our "hunting traditions", it's about having some recourse against a "tyrannical government".

Take it to the appropriate forum. No one in here should have to listen to lunatic rantings of overthrowing our government.

 

[duaneage]

Take it to the appropriate forum. No one in here should have to listen to lunatic rantings of overthrowing our government.

Agreed, but no one is ranting about overthrowing the government. Measure down a bit.

I degree'd cams on my small block ford. I had a combination of very large valves and intake on a small displacement motor with variable cam timing. I used offset keys to adjust the relationship 2 degrees fore or aft. I don't remember if a lagging cam or leading cam did the trick, it was 25 years ago.

What I did was adjust the cams for maximum pressure at cranking speed.This not only helped with starting and idle but restored low end power lost with the larger induction system. There was so much capacity already I could afford to increase efficiency slightly at the low end without impacting power at 7000 RPM.

It could be said that a cam degree adjustment is the ultimate fine tuning for a modified motor. For a stock engine it's not likely to do that much.

 

[reddirtrider]

Agreed, but no one is ranting about overthrowing the government. Measure down a bit.

You have your interpretation, I have mine. What we can agree on is that it isn't appropriate to spew politial opinions in this forum. I do not want to hear yours or his, just as you likely don't want mine.

 

[rapidray]

Hey sixth grader, CHILL out! Do you always take everything too seriously?!! Ray.

 

[mighty13d]

You have your interpretation, I have mine. What we can agree on is that it isn't appropriate to spew politial opinions in this forum. I do not want to hear yours or his, just as you likely don't want mine.

Thanks for hijacking this thread. ANYWAY... Back to the original topic...


Truckah, I will see if I can get some literature on cam timing. I'm always game for video taping maiden voyages if you decide to do something radical with your bike though!!

 

[Guest]

It could be said that a cam degree adjustment is the ultimate fine tuning for a modified motor. For a stock engine it's not likely to do that much.

That's assuming they are properly set to spec, to begin with. For whatever reason, I hear the Suzuki GS cams (my bike included) were simply supplied 'in the ballpark' from the factory. Actually dialing them in with adjustable cam sprockets, made significant difference, in terms of smoothness & power. I wonder why bikes aren't dialed in with adjustable sprockets from the factory.....surely cost cannot be the only reason?
Tony.

 

[duaneage]

That's assuming they are properly set to spec, to begin with. For whatever reason, I hear the Suzuki GS cams (my bike included) were simply supplied 'in the ballpark' from the factory. Actually dialing them in with adjustable cam sprockets, made significant difference, in terms of smoothness & power. I wonder why bikes aren't dialed in with adjustable sprockets from the factory.....surely cost cannot be the only reason?
Tony.

One reason is the changes in cam timing relative to the piston has the greatest benefit when you have serious mods. The stock cams in stock engines are generalized. When you start increasing the cam numbers and airflow, in addition to compression, you end up with more power but at a cost of driveability and idle quality. Degree adjustmemts to both cams together moves the power band around and can reduce an unwelcome peak. Adjusting the exhaust and intake independent of each other is a lot more complicated and can either bring great results or abject failure. There is a lot going on in terms of valve area, intake flow, exhaust flow, piston speed, etc. You really need a dyno and experience with the engine to know what works.

I relied on published specifications in cam selection and head porting but the one variable I had was the variable lifters. They worked as intended but I had a powerband that was still tilted towards the high end. Shifting the cam gave me a lot more power at 2200 RPM where the converter launched and it was easier to start. My engine was really more of a rally car design so I needed to make it more streetable. For those interested, it was a 260 V-8 with 289 heads port matched to a Edelbrock Streetmaster singleplane high rise. 303/280 cam with .475/.450 lift. Carb was Holly 4150 450CFM with two stage powervalve. Small wonder indeed.

GS engines are a lot different than V-8s but the same basic principles apply, Unless you can test carefully each combination, rely on established and tested setups. It will save you time.

 

[reddirtrider]

Hey sixth grader, CHILL out! Do you always take everything too seriously?!! Ray.

This is the second time you've called me names in this forum. It's ironic that children do that, yet you refer to me as one?

I don't visit this forum for political reasons. If you don't understand that it's not my problem.

 

[rapidray]

If you act like one you will get called one. If you don't like what is being posted, if it doesn't APPLY to you , ignore it. I looked at what was posted & didn't feel it needed your comment at all. If you don't want heat back away from the fire. Ray.

 

[reddirtrider]

If you act like one you will get called one. If you don't like what is being posted, if it doesn't APPLY to you , ignore it. I looked at what was posted & didn't feel it needed your comment at all. If you don't want heat back away from the fire. Ray.

I see, so name calling is what you do, then when you're called on it it becomes a debating technique. So, who's the child Ray?

I might have gone a bit overboard on my initial comment. I won't attempt to explain why here, nor will I visit the political section, where his comment should have been posted.

As far as hijacking the thread, the original comment on guns had no degree wheel content, nor has quite a few after that. As a matter of fact, Pos was the only one with any specific information on HOW to actually degree cams.

My suggestion to you Ray, is to speak when spoken to and stop playing the mediator with an attitude.

 

[posplayr]

More links

More links

Here is some more interesting background on heory. Especially the sensitivity numbers highlighted in Red below which would indicate the level of sensitivity to cam degreeing accuracy.

From a practical standpoint, if you want to degree a stock cam, that isall that matters. If you buy an aftermarket cam, it would be worth the money you spend to get it degreed to the closest degree as specificed by the manufacturer. If you are racing well you dot need my advice.

http://instructor.mstc.edu/instructor/candres/studentaccess/Presentations/Unit%204/Camshaft%20Theory%20and%20Design.ppt#256,1,Camshaft Design and Theory

http://www.compcams.com/Technical/TimingTutorial/

http://www.hotbikeweb.com/tech/0711_hbkp_tech_tips_camshafts/final_thoughts.html

Changing Cam Timing: Retarding or advancing a cam 4-degrees will move the engine's power band either up (retarded) or down (advanced) approximately 300 to 400 rpm. Closing the intake valve later and/or opening the exhaust valve earlier tend to move the power band higher. Basically, retarding a cam increases top-end horsepower, while advancing a cam improves low-end torque. If power improves when the cam is retarded more than 4-degrees, the cam is too small and requires more duration. On the other hand, if power increases when the cam is advanced more than 4-degrees, the cam is too large and less duration would probably improve performance. All else being equal, a cam with a later closing intake valve requires an increased mechanical compression ratio to maintain a given low speed performance.

SAMPLE TWIN CAM CAMSHAFTS

Table 2 Valve lift with 1.625:1 rocker arm ratio. *Gear Drive, reverse rear cam rotation.Note the TW37s and TW37b cams have the same amount of duration and lift but the opening and closing valve timings are different, by changing the timing of the opening and closing events, Lobe Center, Lobe Separation Angle, and the amount of overlap change. Also note that duration values change when measured at different tappet lifts, such as .053" and .020". Accurate comparisons can only be made with measurements taken at the same tappet lift.

 

[duaneage]

As a matter of fact, Pos was the only one with any specific information on HOW to actually degree cams.

That's funny, I thought I contributed to this thread. Guess not.

 

[reddirtrider]

That's funny, I thought I contributed to this thread. Guess not.

You did, just not any information on HOW to degree cams, which is what was originally asked, and what I specifically stated. Yes, you did contribute. I never said you didn't. This is turning into something I didn't intend. I appologize to all who read my comments.

 

[rgarcia1983]

whoa, to everyone whos haveing a little argument here, do it over PM's, we dont want to read it, or start something off-topic elsewhere. (personally, i love political banter, so long as its founded) and remember, were all here because we love the same thing (bikes...i hope)

so relax, and share some riding stories, and get over this!

 

[rgarcia1983]

oh, yeah, i forgot to ask, has anyone tried to do this with a 550? im just curious to see what anyone has to say.