How to Guide: Degreeing Cams on 6G72 w/ Pictures

This is How I degreed my cams, there may be a better way, but it's how i did it. I'd love some feedback

Step 1: Find Top Dead Center (TDC) of Number One Cylinder, The Ignition System Stealth316 gives a good layout and explanation of the cylinder layout. This also becomes critical when degreeing the rear cylinder bank.
- There are various way to do this. I used a dial indicator and rotated the
motor until TDC was found. Notice we used some flat iron secured to the
head via middle valve cover holes to secure the iron and thus the dial
indicator base.

http://www.3sgto.org/attachment.php?...7&d=1338140379

Step 2: Setting the Degree Wheel to 0 degrees at TDC. This is a Comp Cam Degree wheel available on summit, you can see the black insert in the middle, it perfectly fits the stock crank pulley bolt. I used an axle nut on the back to space out the degree wheel from the crankshaft for proper clearance (no picture sorry). I used a pointer also available on summit, and you can see I mounted it to the water pump upper bracket.

ONCE YOU SET THE POINTER AND DEGREE WHEEL YOU CANNOT DO TWO THINGS:
1.Touch the pointer.
2.Rotate the engine counter clockwise as this could loosen the crank bolt and throw off your degree wheel.

http://www.3sgto.org/attachment.php?...9&d=1338140683
http://www.3sgto.org/attachment.php?...8&d=1338140677

Step 3: Insert a Solid Lifter and Setup Dial Indicator on Valve Retainer. You must have a solid lifter. Period. I’ll go into more detail later but you want to keep the solid lifter in a loosen position so you can adjust it in car. Also lower the solid lifter all the way down or down far enough that you are confident that it is not preloading the valve. PRELOADING CANNOT EXIST AT THIS STEP.
http://www.3sgto.org/attachment.php?...2&d=1338141009

When arranging the dial indicator on the valve retainer there are several factors to consider:
1.The dial indicator needs to be on a “flat” portion of the retainer with as little curvature as possible.
http://www.3sgto.org/attachment.php?...1&d=1338141004
2.The dial indicator needs to clear the cam shaft with ZERO touching, bumping, rubbing, etc.
http://www.3sgto.org/attachment.php?...4&d=1338154407
3.The angle of the dial indicator needs to be approximately parallel to the angle of the valve stem in 3 planes. Ie if you could extend the valve stem (red line) into space, that line and the dial indicator (yellow line) need to be as parallel as possible (blue lines showing the space between the lines is approximately equal and hence parallel).
http://www.3sgto.org/attachment.php?...0&d=1338141000


Step 4: Setting 0.005” preload by using solid lifter. You’ve probably done this by now, but the cam lobe must be entirely off the valve, ie not depressing the valve (or more accurately in our case, completely off the rocker arm). If Not Rotate the engine until the cam lobe is pointing straight up from the valve (note: this is not straight up to the sky but straight up from the valve stem, ie use the red line from the last picture).

Zero the dial indicator, rotate the motor a few times to ensure that when you return to the completely off lobe position the dial indicator should return to zero. THIS MUST HAPPEN, if it doesn’t return to zero you have a problem and repeat step 3.

Now lengthen the solid lifter until you’ve added 0.005” preload on the dial indicator and lock the solid lifter.

http://www.3sgto.org/attachment.php?...3&d=1338141258

Step 5: Degreeing the Cams. You must have a cam card or detailed cam specifications, in my case I was installing the Brian Crower 272 street cams. NOTE: this cam card won’t work for factory cams or any other cams for that matter. I’ve provided the cam card as an example only. NOTE AGAIN: NEVER ROTATE THE ENGINE COUNTERCLOCKWISE.

Here’s the guide to understanding the abbreviations on the cam card
INT : Intake Valve
EXH: Exhaust Valve
TDC: Top Dead Center
BDC: Bottom Dead Center
ATDC : After Top Dead Center
BTDC: Before Top Dead Center
BBDC: Before Bottom Dead Center
ABDC: After Bottom Dead Center
I.O. : Intake Valve Open
I.C. : Intake Valve Close
E.O. : Exhaust Valve Open
E.C. : Exhaust Valve Close

In the diagram in the bottom half of the cam card, it can be seen: Timing Events Correct at 0.050” Lift , These are the values we will be using.
http://www.3sgto.org/attachment.php?...5&d=1338155276
http://www.3sgto.org/attachment.php?...6&d=1338155353
1.So in the general case, rotate the engine (in the correct direction) until 0.050” lift is achieved on the dial indicator. You need to note the position of the small dial (Red arrow) because this is also the point at which you will be 0.050” from closing. (this picture is just an example, obviously I'm not at 0.050" lift, I just took this picture to show what I was talking about)
http://www.3sgto.org/attachment.php?...7&d=1338155837
2.Note the degree on the degree wheel. (as an example: at 0.050” lift on the intake cam, the degree wheel should be -7 degrees ATDC, this is the same thing as 7 degrees BTDC, I have no idea why brian crower uses the negative system)

3.Continue rotating the engine until you are 0.050” lift from closing (ie the little arrow on the dial indicator will be the same as it was for 0.050” lift after opening in step 1). DONT ROTATE COUNTER CLOCKWISE, Rotate the engine through the full strokes until valve closure occurs.

4.Note the degree on the degree wheel. (example: at 0.050” lift from closing on the intake cam, the degree wheel should be 31 degrees ABDC.

5.Repeat a few times to check your numbers are CONSISTENT (Not necessarily perfectly accurate to the cam card). If not, you have something wrong and the numbers will not be consistent, and go back to step 3 and continue forward again.

6.Now that you have your numbers, using adjustable cam gears adjust the cam timing to the correct for differences.
a.I talked to a couple of people about the best way to do this and in general the consensus is to average the differences. As an example: If you measure the intake opens 4 degrees early and the exhaust closes 2 degrees late, retard
the timing a degree such that the intake opens 3 degrees early and the exhaust closes 3 degrees late. It is believed that the inability to measure directly at the valve stem, and the requirement of the rocker arm for valve depression introduce some 'error' of measurement into the degreeing. Thus the best way is to average the error on both sides of opening and closing and this gives the best timing possible.

7. After adjustment, CHECK to make sure what you just did made the changes you expected. CHECK CHECK AND RECHECK to make sure what you did makes sense.

8.Complete on other cams. Note on the Rear cylinder bank you need to use cylinder number 4 because it is the paired sister cylinder of cylinder 1, and you will not need to reset the degree wheel. SEE Stealth 316 link in step 1.

Reserved for pics2

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Good stuff!

Thanks for the write up!

Grrrrrreat write up!

Very nice!

Looks like you documented the process pretty well... Thanks for taking the time. I'm not sure I've seen anyone else do it on any of the forums, and for someone who's never done it before, I could see this being a big help.

Just a bit useless trivia: I got my first real wrench turning job in 1982 while sweeping floors in a trans shop, trading for a trans repair in my 70 SS 396 Chevelle... The owner was into ridiculously fast big block Chevy powered boats, and I was the first kid he'd run across that knew how to degree a camshaft. He offered me a job the next day...

Another method you may want to check out (I usually do both the check my results, if they don't match, I know to check for errors) is to locate and degree to the lobe centerline. This method will also work for stock cams, because that information is published in factory tech info.

awsome. man how do you like the solid lifters? how often do you have to re-adjust yours?

Quote:

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Originally Posted by keo92stealth

awsome. man how do you like the solid lifters? how often do you have to re-adjust yours?

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I don't know what the OP is using in his car, but in this context he was simply using a solid lifter to degree the cams(and stating the fact that it is a required tool for the task)... He may very well be running stock hydraulic lash adjusters in operation.