Author Topic: LookING for Camshaft knowledge  (Read 3196 times)

Offline ViperMan

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LookING for Camshaft knowledge
« on: January 18, 2008 - 04:41:25 PM »
Hey guys,

Does anyone know of any good technical websites that'll explain things like lift and duration without me having to ask you guys a ton of questions?

I mean most companies list their cam shafts with things like "stock," "mild performance/RV" "light drag," etc...  I just thought that maybe instead of pointing at a general description and saying, "That one!" it might be nice to know what the technical numbers mean.

Any links/info would be appreciated!

Jeff
« Last Edit: January 18, 2008 - 06:01:14 PM by 73Barracuda »
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2005 Jeep Grand Cherokee Limited - Trail Rated - 4.7L V8, Auto
2010 Dodge Challenger SE Rallye - 3.5L V6, Auto (Wife's!)




Offline 70_challenger

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Re: Look for Camshaft knowledge
« Reply #1 on: January 18, 2008 - 05:50:07 PM »
http://www.compcams.com/Information/Tutorials/

Read through that tutorial, but then click on the graph to enlarge it. 
That graph describes the valve timing events really well. 

And don't be afraid to ask - That stuff is interesting to talk about!

-Tom
« Last Edit: January 18, 2008 - 05:53:18 PM by 70_challenger »

Offline ViperMan

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Re: LookING for Camshaft knowledge
« Reply #2 on: January 18, 2008 - 06:47:02 PM »
So basically I could spend a bajilion hours trying to determine what lobe separation angle I want and the valve depth and try to custom order one, or I can just point and say "Yeah that looks about right" and be done with it.  :)

I'm thinkin' a light drag performance cam for my 440 project - Mopar has a Purple Shaft cam with power range from 1,300 to... ...I don't remember what...  ...5,700 (just grabbed the book.)  Lift is .455/.455, 272/272 duration with a 112 centerline.  48-degree overlap.  I figured power at 1,300 will give me a mild lop but not be too annoying, and should be reasonable for highway cruising.

Engle has a cam with slightly more lift and power starting at 1,500rpm, but I'm thinkin' that might lop just a bit too much for my comfort.

What do you think?

Jeff
2000 Dodge Viper GTS Coupe - 8.0L V10, 6-Speed Tremec
2005 Jeep Grand Cherokee Limited - Trail Rated - 4.7L V8, Auto
2010 Dodge Challenger SE Rallye - 3.5L V6, Auto (Wife's!)

Offline MEK-Dangerfield

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Re: LookING for Camshaft knowledge
« Reply #3 on: January 18, 2008 - 07:03:24 PM »
Jeff,

  What gears do you have in the rear? I have a cam that doesn't kick in until 2500 RPM, but it sounds mean at idle. The problem is, with my 3:23 gears, that's 55-60 MPH before it does it's thing. Let me tell Ya, if I punch it on the Hiway, it wants to throw me in the back seat!!   :scared: The cam is overkill for me, but I keep it since it sounds so good loping along. You might want something a bit milder. Mine is a Lunati, but I think a cam that kicks in at 1500 RPM should be your minimum. Also, with a bigger cam, you have to take into consideration the rear gears and how you drive to figure out what torque converter to go with... All a big can of worms. 


  Mike

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Offline ViperMan

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Re: LookING for Camshaft knowledge
« Reply #4 on: January 18, 2008 - 07:09:43 PM »
Hang on hang on hang on...

You want me to go milder than 1,300 rpm but say 1,500 rpm is my minimum??

I thought lower rpm's was a milder cam, higher RPM was a "bigger" cam - that's why they say they're for "Drag Moderate Competition."  They start at 2,600 RPM, (one is 3,600!) and have overlaps of over 60 degrees, .509" of lift, etc.

So help me out - am I backwards on something?

Also, I really want roller tappets for decreased friction, but they look hard to come by unless you're going with a super serious drag cam...  Is that pretty much the rule?  Do I have to go with a custom grind to get roller tappets in my performance range?

Jeff
2000 Dodge Viper GTS Coupe - 8.0L V10, 6-Speed Tremec
2005 Jeep Grand Cherokee Limited - Trail Rated - 4.7L V8, Auto
2010 Dodge Challenger SE Rallye - 3.5L V6, Auto (Wife's!)

Offline MEK-Dangerfield

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Re: LookING for Camshaft knowledge
« Reply #5 on: January 18, 2008 - 07:39:56 PM »
Hang on hang on hang on...

You want me to go milder than 1,300 rpm but say 1,500 rpm is my minimum??

I thought lower rpm's was a milder cam, higher RPM was a "bigger" cam - that's why they say they're for "Drag Moderate Competition."  They start at 2,600 RPM, (one is 3,600!) and have overlaps of over 60 degrees, .509" of lift, etc.

So help me out - am I backwards on something?



Jeff

Who are you talking to? The stock cam probably kicked in at 1200 RPM. Go 1500 RPM at least.  Yes, lower RPM's is a smaller cam.

Mike

1970 Challenger - SOLD
2016 SXT+.  1 of 524 SXT+'s in Plumb-crazy for 2016.

Offline Chryco Psycho

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Re: LookING for Camshaft knowledge
« Reply #6 on: January 18, 2008 - 10:10:36 PM »
I wrote a couple fo basic articles in the archives
ask ???s as nessisary

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Offline GoodysGotaCuda

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Re: LookING for Camshaft knowledge
« Reply #7 on: January 18, 2008 - 10:37:44 PM »
Just quick terms i guess

Lift, amount of ramp over base circle on the cam. Usually the advertised figure is multiplied by the rocker arm ratio (factory 1.5). This figure can be calculated out if you decide to run aftermarket rocker arm ratios. More air you can get in and out, the more potential for power. However piston-to-valve clearance must be taken into consideration. Often the exhaust valve lift is more to reduce the 'pumping' action of the engine and to rid the cylinder of as much exhaust as possible so it doesnt dillute the incoming air/fuel charge.


Duration, the amount of crankshaft degrees of rotation the valve is open - Overlap is calculated using IVO (intake valve opening) and EVC (exhaust valve closing) numbers and added. Generally the higher the overlap, the higher the 'powerband'. Does depend on intended use, Nitrous, Turbo, N/A, etc.

Centerline - The cam is rotated to that lobe's maximum lift, it is then turned .050" clock and counter-clockwise. Addition of the two numbers of crank rotation divided by two is your lobe centerline. Intake centerline is usually the figure needed in order to 'degree' your cam. And it must be found while installed in the block using a degree wheel, that figure will compare to the cam card's centerline in order to figure if the cam is straight-up, retarded or advanced. Adjustments can be made to what you are looking to gain. Retarding the cam can 'generally' increase hp, while hurting low end torque, vise-versa for advancing the cam.

Lobe Separation - Addition of intake and exhaust centerline figures, divided by two. Not the most useful figure in the mix..

Hope it helps some, cam degreeing isn't difficult if it is explained right. Make sure you do so when you decide you install your cam to get the most out of your new bumpstick
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nivvy

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Re: LookING for Camshaft knowledge
« Reply #8 on: January 20, 2008 - 09:03:47 AM »
Solid Roller - Get more lift and less duration which is better for idle quality..... but you all know my style.....  :working:

Jeff I really like the camquest 6 program... you can put in all your specs and it chooses th right cam for you and gives you several options... takes the guss work out........ and gives you est. HP for every cam you select  :2cents:
« Last Edit: January 20, 2008 - 06:32:33 PM by StRoKer »

Offline hemiken

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Re: LookING for Camshaft knowledge
« Reply #9 on: January 20, 2008 - 09:06:43 AM »
Solid Roller - Get more lift and less duration which is better for idle quality..... but you all know my style.....  :working:

Jeff I really like the camquest 4 program... you can put in all your specs and it chooses th right cam for you and gives you several options... takes the guss work out........ and gives you est. HP for every cam you select  :2cents:
Hey Stroker,

Where do you get that camquest 4 program from ? :1zhelp:
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Offline FJ5_440

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Re: LookING for Camshaft knowledge
« Reply #10 on: January 20, 2008 - 09:42:01 AM »
Download it free here:
http://compcams.com/Camquest/
** Shane **

Offline hemiken

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Re: LookING for Camshaft knowledge
« Reply #11 on: January 20, 2008 - 09:47:21 AM »
Download it free here:
http://compcams.com/Camquest/

Thanks FJ5_440,

Your a legend and a he!! of a nice color.
1970 Barracuda   (O^--^===|===^--^O)
1971 Barracuda   (O O {]{]{]|[}[}[} O O)
1970 Challenger  (O O [======R/T=] O O)
1971 Challenger  (O O ===== ===== O O)
I pay homage to the best Mopars ever built.

Offline vert

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Re: LookING for Camshaft knowledge
« Reply #12 on: January 20, 2008 - 11:07:20 AM »
Jeff,
If you aren't an expert, call a cam manufacturers tech line.  They can recommend something and have a vested interest in your satisfaction.  For your educational enjoyment, read others advice here, and check this excellent article http://victorylibrary.com/mopar/cam-tech-c.htm at the Victory Library http://victorylibrary.com/mopar/mopar-tech.htm where you'll also find good info on Mopar cam profiles.
Good luck. -Alan
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nivvy

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Re: LookING for Camshaft knowledge
« Reply #13 on: January 20, 2008 - 06:33:13 PM »
I bought mine... I dont know if free download gives you ll options???

Offline ViperMan

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Re: LookING for Camshaft knowledge
« Reply #14 on: January 21, 2008 - 10:45:43 AM »
Awesome information - thanks guys.

Jeff
2000 Dodge Viper GTS Coupe - 8.0L V10, 6-Speed Tremec
2005 Jeep Grand Cherokee Limited - Trail Rated - 4.7L V8, Auto
2010 Dodge Challenger SE Rallye - 3.5L V6, Auto (Wife's!)