ICL vs. .050” Cam Degreeing Methods

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ICL vs. .050” Cam Degreeing Methods

Post by BBO Omega »

I know that Crane recommends the .050” Tappet Lift as the preferred method for Degreeing Asymmetrical ground Camshafts. What do the professionals on here that do this for a living have to say. I know as a novice, the .050” method is very simple and repeatable.
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Re: ICL vs. .050” Cam Degreeing Methods

Post by Walter R. Malik »

I do it however THAT camshaft company wants me to install THEIR particular camshaft ... so, both ways can be deemed correct.
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Re: ICL vs. .050” Cam Degreeing Methods

Post by elwood »

^^ this ^^

mathematical centerline on an asymmetric lobe is a red herring, the .050" lift figure will be in the wrong place
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Re: ICL vs. .050” Cam Degreeing Methods

Post by pastry_chef »

Check Mike Jones comment, third post down.
https://www.speed-talk.com/forum/viewtopic.ph ... 3&p=725662
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Re: ICL vs. .050” Cam Degreeing Methods

Post by elwood »

i agree that max lift has much less effect than open & close points, by definition they define valve timing events

whatever happens or doesn't in between comes out in the wash, but if somebody were to get all scientific, overthink the grinder and use an alternate install procedure rather than the specified method they'd just be howling at the moon. on the other hand if that somebody knows what they're doing and uses actual open & close points to reference the cam where they want it, more power to them pun intended
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Re: ICL vs. .050” Cam Degreeing Methods

Post by user-23911 »

If you're doing the job for yourself (it takes lots of time) then set the lash to zero or a bit less, use a dial gauge and measure cam lift vs degrees. That way you get the full picture and of course it works with any unknown cam profile.
Once you've done it with cylinder 1, repeat for every other cylinder, that way you'll know what's right and what's not right, including the measurement method.
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Re: ICL vs. .050” Cam Degreeing Methods

Post by Stan Weiss »

How was the cam designed to be run?

The green line is a symmetrical lobe

The blue and magenta are the same asymmetrical lobe. One set so that the open and closing points are the same as the symmetrical lobe and the other so than the point of max lift is the same as the symmetrical lobe.

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ab-cam-sym-asym-asym.gif
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Re: ICL vs. .050” Cam Degreeing Methods

Post by statsystems »

Stan Weiss wrote: Mon Jul 09, 2018 2:44 am How was the cam designed to be run?

The green line is a symmetrical lobe

The blue and magenta are the same asymmetrical lobe. One set so that the open and closing points are the same as the symmetrical lobe and the other so than the point of max lift is the same as the symmetrical lobe.

Stan

ab-cam-sym-asym-asym.gif


The way I'm reading your graph is how Harold Brookshire explained it to me in probably 1989ish. He wanted the ICL where he wanted it because he said you can have the lifter move through .050 lift the same but have an entirely different ICL.

Am I reading your graph correctly?
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Re: ICL vs. .050” Cam Degreeing Methods

Post by vannik »

Stan Weiss wrote: Mon Jul 09, 2018 2:44 am How was the cam designed to be run?

The green line is a symmetrical lobe

The blue and magenta are the same asymmetrical lobe. One set so that the open and closing points are the same as the symmetrical lobe and the other so than the point of max lift is the same as the symmetrical lobe.

Stan
Stan,

This is why a while back I tried to get the definitions of "lobe centre" and "lift centre" clearly defined but got very few takers. Your picture makes it very clear that they are not the same, thanks for posting this.

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Re: ICL vs. .050” Cam Degreeing Methods

Post by hoffman900 »

vannik wrote: Mon Jul 09, 2018 9:31 am
Stan Weiss wrote: Mon Jul 09, 2018 2:44 am How was the cam designed to be run?

The green line is a symmetrical lobe

The blue and magenta are the same asymmetrical lobe. One set so that the open and closing points are the same as the symmetrical lobe and the other so than the point of max lift is the same as the symmetrical lobe.

Stan
Stan,

This is why a while back I tried to get the definitions of "lobe centre" and "lift centre" clearly defined but got very few takers. Your picture makes it very clear that they are not the same, thanks for posting this.

Neels
I’ll have to dig up the old thread of Harold, MJones, and Mike Sloe (spl?) arguing about this.
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Re: ICL vs. .050” Cam Degreeing Methods

Post by 77cruiser »

I'd tend to believe the LC is 1/2 way between the opening & closing & not necessarily the peak lift. symmetrical lobe would probably be peak lift. Asymmetrical maybe, maybe not.
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Re: ICL vs. .050” Cam Degreeing Methods

Post by CamKing »

hoffman900 wrote: Mon Jul 09, 2018 10:16 am I’ll have to dig up the old thread of Harold, MJones, and Mike Sloe (spl?) arguing about this.
Please don't.
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Re: ICL vs. .050” Cam Degreeing Methods

Post by hoffman900 »

CamKing wrote: Mon Jul 09, 2018 1:32 pm
hoffman900 wrote: Mon Jul 09, 2018 10:16 am I’ll have to dig up the old thread of Harold, MJones, and Mike Sloe (spl?) arguing about this.
Please don't.
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Re: ICL vs. .050” Cam Degreeing Methods

Post by Stan Weiss »

statsystems wrote: Mon Jul 09, 2018 3:45 am
Stan Weiss wrote: Mon Jul 09, 2018 2:44 am How was the cam designed to be run?

The green line is a symmetrical lobe

The blue and magenta are the same asymmetrical lobe. One set so that the open and closing points are the same as the symmetrical lobe and the other so than the point of max lift is the same as the symmetrical lobe.

Stan

ab-cam-sym-asym-asym.gif


The way I'm reading your graph is how Harold Brookshire explained it to me in probably 1989ish. He wanted the ICL where he wanted it because he said you can have the lifter move through .050 lift the same but have an entirely different ICL.

Am I reading your graph correctly?
That would be the magenta line. But as Neels said what do we define the icl as?

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Re: ICL vs. .050” Cam Degreeing Methods

Post by statsystems »

Stan Weiss wrote: Mon Jul 09, 2018 2:58 pm
statsystems wrote: Mon Jul 09, 2018 3:45 am
Stan Weiss wrote: Mon Jul 09, 2018 2:44 am How was the cam designed to be run?

The green line is a symmetrical lobe

The blue and magenta are the same asymmetrical lobe. One set so that the open and closing points are the same as the symmetrical lobe and the other so than the point of max lift is the same as the symmetrical lobe.

Stan

ab-cam-sym-asym-asym.gif


The way I'm reading your graph is how Harold Brookshire explained it to me in probably 1989ish. He wanted the ICL where he wanted it because he said you can have the lifter move through .050 lift the same but have an entirely different ICL.

Am I reading your graph correctly?
That would be the magenta line. But as Neels said what do we define the icl as?

Stan
That is an issue for sure. I suspect the actual answer is center of max lift is actually where the cam ends up, not actual LSA.
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