# Sticky  Degreeing a Cam - the process



## BearGFR (Aug 25, 2008)

As it turns out, just as there's a discussion going on about the topic, just today I got to the point where it was time to degree the cam in my engine so I thought I'd document the process here for reference.

To start with, here's a copy of my cam card. Notice that the specs recommend these instructions: "DEGREE INTAKE LOBE TO 106". 








What the heck does that mean? It means the cam vendor recommends that the camshaft is installed in an orientation, "timing" if you will, such that the cam's intake lobe reaches its peak lift, its highest point, at the same time that the crankshaft is at 106 degrees. 106 degrees what? Well, remember that the intake valve both opens and closes BEFORE compression can start, so it means they want that point of peak lift to happen 106 crankshaft degrees before #1 cylinder reaches top dead center. Ok? Ok.

How do we do that? We need some tools - of course. We need a degree wheel, and ideally, a dial indicator with a magnetic base.

The first order of business is to install the degree wheel and orient it so that it accurately reflects where Top Dead Center is. Unfortunately I didn't think to take photos of how I did that, but there are plenty of references out on the internet that show how. You can use a piston stop to do it, or you can use the dial indicator that you're going to need anyway, which is what I did. To accurately locate TDC with a dial indicator, the best way is to find two points _on either side_ of TDC, such as when your indicator reads 0.020 below peak, note the reading on your degree wheel (the actual numbers don't matter at this point), then split the difference between those two for TDC. For example, say your degree wheel reads 27 degrees when your dial indicator says 0.045, and the readings on the dial indicator are getting smaller the more you turn the crank shaft. At some point they'll stop getting smaller and will start getting larger again. When the reading on your dial indicator gets "back to" 0.045, your degree wheel shows 87 degrees. You know that halfway between 27 and 87 is where TDC was, so next you keep turning the engine over until you go past 27 again and get to 57 (57 is exactly halfway between 27 and 87) - now you're at true TDC. Always turn it in the same direction as it runs so that if there's any slack in your timing chain it won't distort the readings. Now, being very careful NOT to move the crankshaft any, loosen the bolt on your degree wheel and rig up a pointer (I use a stiff wire under a bolt in one of the timing cover bolt holes) so that it points to ZERO on your wheel. Now you're set to continue. Here's what setup looked like after I did all that. (It sounds more complicated than it is).









Next step is to move your dial indicator set up over so that you can read the lift on INTAKE lifter #1. The actual readings don't matter because all we're going to care about again is finding two points on "either side" of peak lift where the amount of lift is the same, and take readings from our degree wheel at those two points.

Here's what my setup looks like now








Notice that the intake lifter is already starting to come up, and the reading on my dial indicator is showing 0.4400. This cam doesn't have 0.4400 lift by any means. Peak lift is actually 0.4300 if you remember from the cam card. Again, the actual reading doesn't matter. I just have to remember it, and also note the reading on the degree wheel at this point. Which was this:








I kept turning the crank slowly, watching all the while what my dial indicator was doing. I saw the readings continuing to go up, then start decreasing after the lifter had "passed through the point of peak lift. When it got "back to" 0.4400 again, I took another reading on the degree wheel and found it was reading 146 degrees.








Cool. Now all that's left is to again "split the difference" between the two readings: (67.5+146) / 2 = 106.75 So my intake centerline is at 106.75 degrees. 
Perfect. I say perfect because my timing set can only provide adjustments in 2 degree increments, so the two settings available to me on either side would have been 104.75 or 108.75, so that's why I say that 106.75 is perfect.

As an aside, in order to get this 106.75 I actually have to use the +4 settings on my timing set. If I had installed this cam "straight up" using the factory timing marks, it would have actually been at 102.75. This is why you always degree new cams. This is actually the second time I've set this particular cam up in this engine, so I already knew what it was going to take to get it right. Otherwise I would have started by installing it "straight up" using the factory marks, checked it, and then adjusted from there.

I hope this is helpful.

Bear


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## PontiacJim (Dec 29, 2012)

Bear: "As an aside, in order to get this 106.75 I actually have to use the +4 settings on my timing set. If I had installed this cam "straight up" using the factory timing marks, it would have actually been at 102.75. This is why you always degree new cams. Otherwise I would have started by installing it "straight up" using the factory marks, checked it, and then adjusted from there."

PJ: OK,that educates me on the +4. *Army* was asking this question on his Butler cam spec, 112+4. I had assumed that the cam said to install at 108 and the +4 was added to that to come up with the 112.

I also assumed that the added 4 degrees built into the cam was designed to be installed "straight up" using the factory cam/crank gear dots. This is how Pontiac did their factory cams, 4 degrees built into the cam and you lined up your gears dot-to-dot. But you say that is not the case and the cam would have been retarded 4 degrees @ 102.75?

Why did you not check the exhaust center line (ECL) and check to see if the cams' LSA was accurate. The ICL & ECL added together and divided by 2 should equal the 110 LSA, right? So the exhaust center line should have come up as 113.25 on the cam wheel.

And....... will this process work with a hydraulic lifter or should a solid lifter always be used to dial in the cam?


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## BearGFR (Aug 25, 2008)

I think you're right, Jim, when you said 


> "I also assumed that the added 4 degrees built into the cam was designed to be installed "straight up" using the factory cam/crank gear dots."


I've been told before that it's not unusual for new cams to be a little "off" for one reason or another, so that's why that information is always provided on the cam card with regard to there it "should" be installed. On any unknown or new cam, I'd recommend always starting with it installed "mark to mark" and then measuring with a degree wheel to see where that puts the ICL. If it doesn't end up where the grinder recommended, only then do you "mess with it". If I'd installed THIS cam 'mark to mark', yeah it would have been 4 degrees retarded but I don't think that's necessarily the case with every cam, or even every different instance of the other cams of the exact same version/model as this one.

On all the engine building shows, they always make a big deal out of "degreeing the cam". There must be a reason they do that instead of just installing them 'mark to mark', and I assume it's because of the possibility of variance.

Why didn't I check the exhaust lobe? It didn't occur to me to  I might set up again tomorrow and do that just for grins.

I don't know why you couldn't use a hydraulic lifter for the process, just be sure that the dial indicator doesn't depress the plunger when measuring. To be safe, set it up so that the indicator is reading off the 'edge' of the lifter body and not the plunger.

Bear


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## MidnightAuto (May 28, 2018)

exactly. If you install dot to dot and the results match up with the card, then you are done. you have degreed the cam in- which seems to me as a fancy way of saying I checked that the card matched real life.

but as bear mentions, many say that manufacturing variances often make it so that after going dot to dot, if your readings don’t match the card, then at that point you are either advancing or retarding the cam to get to the desired icl. This is accomplished with a multi key way timing chain, or an offset cam key from a mopar.


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## armyadarkness (Dec 7, 2020)

Thanks for this. You and Jim have been helping me to make sense of it all...

On the thread in question, which I posted below as a reference for anyone trying to educate themselves, I show the card for my present cam, also a Bullet. It has the same note "Install at 106".

My question was, am I supposed to do that? If so, that explains why my performance was lackluster... Since it was installed "dot to dot".

My new Comp Cam from Butler, which I also posted the card for, says to install it at 108. My intention was to install it "dot to dot". But if Im following what you all are saying:

The new cam centerline "should" already be 108, IF the cam is installed 'dot to dot" and IF the manufacturing tolerances were all true. If not, then it's my job to get the centerline to be 108, either by advancing or retarding the timing, using the 2 degree increments on the crank gear?









HMMMMMM! A POTENTIALLY CONFUSING REVIST OF TIMING AND CAMS


So, I was going to figure this out on my own, but my head exploded, so I figured I'd let you experts chime in on it. I've really been wrestling with performance since December of 2020. Power is lower than I want it to be and it WAS better before I started tweaking the timing. Man I have tweaked...




www.gtoforum.com


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## BearGFR (Aug 25, 2008)

> On the thread in question, which I posted below as a reference for anyone trying to educate themselves, I show the card for my present cam, also a Bullet. It has the same note "Install at 106".
> My question was, am I supposed to do that?


Yes, you're supposed to do that. But installing it "dot to dot" does not _NECESSARILY_ mean that it ended up being somewhere other than at 106. Most cam grinders_ intend _for a 'dot to dot' installation to end up with the cam ICL being where they say it should be. HOWEVER, for reasons I freely admit aren't completely known to me, it sometimes doesn't work out that way. Maybe they're making a "run" of several different cams on their grinding machines and didn't change the indexing settings, either by accident or on purpose. Maybe it has some other cause entirely - I really don't know. I just know that it's always a good practice to use a degree wheel to make certain that the ICL ends up where they say it should be.



> If so, that explains why my performance was lackluster... Since it was installed "dot to dot".


Well, it _might_, that is if it ended up way off from where they wanted it. But unless you check it using a degree wheel to measure how it was originally installed, you'll never know for sure.



> My new Comp Cam from Butler, which I also posted the card for, says to install it at 108. My intention was to install it "dot to dot". But if Im following what you all are saying:
> The new cam centerline "should" already be 108, IF the cam is installed 'dot to dot" and IF the manufacturing tolerances were all true. If not, then it's my job to get the centerline to be 108, either by advancing or retarding the timing, using the 2 degree increments on the crank gear?


Yep, you got it. Always check any new cam and then "do whatever you have to" in order to place the ICL where the vendor says it should be. That is, _unless_ you have a very good reason and specific objective for deviating from that, and you fully understand what the results will be of doing it. In any case, _ALWAYS_ measure it.

This link on the Summit site (again) does a pretty good job of describing what "straight up", "advanced", or "retarded" means along with the expected results of each. There's a misconception that "straight up" means "dot to dot" or "mark to mark", but that perception is incorrect and that's not what "straight up" actually means. What "straight up" really means is that the LSA is "centered" around TDC. That is, if the intake centerline is at 106, then the exhaust centerline will ALSO be at 106. (And the LSA itself will be 106 _cam _degrees). When someone says a cam has X amount of degrees of advance (or retard) _ground in_, what that really means is that the cam LSA is _different _from the recommended Intake CenterLine (ICL). It's a confusing term that I personally wish had never come about, because people see that a cam has X degrees of advance "ground in" and they start thinking that maybe they somehow need to compensate for that when they install it. They don't. Always put the ICL where the supplier says it needs to go, and everything else takes care of itself. Again, there's a good definition of what "ground in" means at Summit.

Bear


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## armyadarkness (Dec 7, 2020)

BearGFR said:


> Yes, you're supposed to do that. But installing it "dot to dot" does not _NECESSARILY_ mean that it ended up being somewhere other than at 106. Most cam grinders_ intend _for a 'dot to dot' installation to end up with the cam ICL being where they say it should be. HOWEVER, for reasons I freely admit aren't completely known to me, it sometimes doesn't work out that way. Maybe they're making a "run" of several different cams on their grinding machines and didn't change the indexing settings, either by accident or on purpose. Maybe it has some other cause entirely - I really don't know. I just know that it's always a good practice to use a degree wheel to make certain that the ICL ends up where they say it should be.
> 
> 
> 
> ...


Awesome! In my eyes, cam and ignition timing are the most complex aspects of our cars, so understanding them is a real asset. 

On a related subject, anyone have "break-in" opinions for a roller cam with the old lifters? I cant see what there is to break in, but I cant find a straight answer on the web.


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