Degreeing a cam

aer212

aer212

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I'm thinking about doing a cam since my engine is getting pulled I figure now is the time to do it. Since doing some research on it, it looks like everyone is saying to degree the cam in. What is this and how is it done?
 
on a Cummins what it is is expensive, a pain in the butt, and time consumin because of the pressed on gear
 
what it is is figuring out where the number one int lobe is in relation to the crankshaft

more specifically where (if you drew a line straight thru the middle of the #1 int lobe, from heal to nose) where that line is to #1 piston when its exactly on tdc

all it takes is a degree wheel and a dial indicator

little bit of knowledge and a lot of patients

if you go to the web cam site they describe the proceedure very clearly

http://www.webcamshafts.com/

on the left side there is a link - degree your cam'
 
It's no different than any other engine. If you do a search on how to degree a cam you'll find plenty to read. It is tougher because you have to press the cam gear to make a change. You will also need an off set key way if you need to change it.
 
Depending on the cam, you may want to check valve to piston clearance on the exhaust valve.
 
that should be checked any time you build a new motor

or move a camshaft

both valves

every hole

if you want to do it right
 
Either with model clay on top of the piston or you can use test springs on the valve and check travel.
 
The problem that I have found with test springs is that all too often the pressures are not exact across the entire range of lift, and one valve opens sooner and higher than the other. This will give you a false opening event and false valve to piston clearance. If it is a drop in cam there is not a lot of benefit in degreeing them in and checking clearances unless you have had your head and/or block decked. Typically it becomes more of an issue to degree in a cam when you have an aggressive custom with a lot of duration.



Zach
 
Hamilton Cams said:
The problem that I have found with test springs is that all too often the pressures are not exact across the entire range of lift, and one valve opens sooner and higher than the other. This will give you a false opening event and false valve to piston clearance. If it is a drop in cam there is not a lot of benefit in degreeing them in and checking clearances unless you have had your head and/or block decked. Typically it becomes more of an issue to degree in a cam when you have an aggressive custom with a lot of duration.



Zach
Click to expand...

So I don't need to degree it if I get a drop in replacement for a 6.7?
 
the cam is the brain of the engine

for making power where it gets installed is as important as having a round straight hole in every cyl

imo
 
Hamilton Cams said:
The problem that I have found with test springs is that all too often the pressures are not exact across the entire range of lift, and one valve opens sooner and higher than the other. This will give you a false opening event and false valve to piston clearance. If it is a drop in cam there is not a lot of benefit in degreeing them in and checking clearances unless you have had your head and/or block decked. Typically it becomes more of an issue to degree in a cam when you have an aggressive custom with a lot of duration.



Zach
Click to expand...

I wouldn't take a reading off the rocker to degree it in. That should be done it the lifter. It takes a little more attention to detail checking clearance with test springs than it does with clay. If it's a direct replacement cam there shouldn't be an issue. Zach is correct about custom cams with more duration.
 
yup Chrysler makes an offset key kit with 1,2,3,4,5 degree keys $58.
machine shop time to press the gear on n off a couple times, plus your time

but necessary for sure for all of the afore mentioned reasons in the other posts
 
I'm guessing using the cam gear with the timing pin is not accurate way to find TDC?
 
As with anything in a High Performance engine, you should check it , there are tolerances to any mass manufactured engine , this is the geartrain and the crank pin location .

I have degreed in a 1000 cams over the years, and it’s not hard, but I understand for those that have never done this before. I have walked quite a few thru it in the last few years.


Just like on a P pump you would not just put it in with the pin, there is a lot of lost tuning opportunities if you do.
A Cam program is just the same. you get out of it what you are willing to put in to it , all engines respond differently to any new part , and the fine tuning is important to finding the last bit of power.

Drop in cams are fine for mild street performance, and will always be the easier out. If you want to really, go to the next level, then a cam profile that really rocks will have to be clearance in the engine. This is achievable without cutting the pistons , with a little work .

When you are going to go all the way and don't mind cutting pistons, then you should figure valve clearance for the pistons before you cut, thereby cutting the minimal amount.


To check clearance , simple clay is not the way to go, I take valve clearance at 15, 10 ,5 before Top Dead Center , at TDI and 5,10,15 After Top Dead Center on both the intake and the exhaust .


Remember the pistons chases the exhaust valve shut, and the intake valve chases the pistons down. Advancing the cam gains, you exhaust clearance and gives up intake clearance. This is because you start the intake event earlier, opening the intake valve as the pistons in coming up and rocking over TDC.

Retarding the cam gains you intake clearance and gives up exhaust clearance. If you know you clearance when you degree a cam in , you know the possibility’s and how far you can move in each directions
In the higher end engine development programs, we work on both at the same time advancing the exhaust and retarding the intake event.


Off on a tangent, we are only scratch the surface, on diesel development work, compaired to the work we did on gas program over the last 25 years.

The number one deal is rocker ratio. I have new rockers systems going on engine for this next season in 2.6 and 2.8 classes. this along with matching cam profiles will give huge gains in airflow



The best-ported Diesel heads suck relativity, in airflow potential, in relation to the requirement of these engines.
These heads want dramatically higher lifts then we have yet seen. On the 24 valve head, the lift numbers would scare most, but these are not a problem, with well-designed valve train programs.

Such development parts, as 60 mm cams, extreme high ratio rocker systems, and other related components are a reality

Well back to the question, if you want a cam in right, degree it in. No one can promise where it will land in any mass produced engine
 
seeker1056 said:
yup Chrysler makes an offset key kit with 1,2,3,4,5 degree keys $58.
machine shop time to press the gear on n off a couple times, plus your time

but necessary for sure for all of the afore mentioned reasons in the other posts
Click to expand...

you can get the offset cam keyways in 1/4 degree increments from Jeff at Mumau Diesel.
 
How far off would a extreme cam be off if you just ligned up the "0" & "00" ?
 
If a cam was ground from a blank to installed centerlines there should be no adjusting whatsoever. Factory gears typically have a +/- .5 degree variation which is pretty close and should not need adjustment. If you run a custom cam and you don't have flycuts then degreeing and checking piston to valve clearance is important. If you run a custom you should just plan on cutting the pistons.

If a cam is reground onto a factory cam, which a lot of aftermarket cams are, then you will need to use offset keys to make sure centerlines are correct. This is due to the fact that there is only so much modification that can be done in grinding to the factory centerlines without eating up too much of the cam. Most of the adjustments will have to be done with offset keys on regrinds. That fact should shed a little light on who runs regrinds and who does not.

Zach Hamilton
 
What if your cam manufacture will not tell you what the intake centerline is supposed to be?
 
Find a different cam source. Installed centerlines are as important as what grind you have. If they are not disclosing that information they either 1) don't know the answer or 2) are afraid you might learn too much and see they aren't doing anything special. Just some common things I have seen on turbos, injectors, pumps, springs etc.

Don't just give people money because they have a fancy logo, make them earn it. It is a business transaction, there are numerous cam manufacturers out there and since you have the money, you have the negotiating power. Use that as leverage!

Zach
 
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