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

[oohnoo]

Now you confusing me as they're not stock cams. What may work for stock cams I'm not sure if they will for aftermarket cams. With my old setup I just put them at +1, -3, but once I degree'd them as everyone suggested doing with any aftermarket cams I'm going to leave them there for now till it gets on the dyno.

DR street cams are designed to work at 110° LC (lobe center) Specs for the cams are as follows:

Intake Exhaust
Valve Lift .400" .400"
Duration 218° 218°
Duration @ .050 200° 200°
Lobe Center 110° 110°

Intake Opens -10° Before TDC Exhaust Opens 30° Before BDC
Intake Closes 30° After BDC Exhaust Closes -10° After TDC

Valve Timing is checked with zero valve lash @ .050 inches of valve lift.

[Ninja Performance]

Those numbers I had listed above. To get the cams in spec the cam gears are set as follows:
#1 Intake = +.4°
#1 Exhaust = +1
#4 Intake = -.1
#4 Exhaust = -.5

You had to set what cam gears? Are you sure the adj cam gears were true? Were the DR cams found to be off using a stock cam gear or an aftermarket adj gear set to 0?

-Chris

[oohnoo]

I have Fidnenza cam gears that are about 5 years old. Ya saw that thread about 3sx cam gears so not really sure if mine are spot on. But would it really matter now that I degree'd the cams. The settings I show are now the "True" zero's yes?

http://i301.photobucket.com/albums/n...4/CamGears.jpg

You had to set what cam gears? Are you sure the adj cam gears were true? Were the DR cams found to be off using a stock cam gear or an aftermarket adj gear set to 0?

-Chris

[oohnoo]

Found the old thread on these which you supplied your expertise.

Fidenza Cam Gears - Extra Safety! - 3000GT/Stealth International Message Center

[J. Fast]

You had to set what cam gears? Are you sure the adj cam gears were true? Were the DR cams found to be off using a stock cam gear or an aftermarket adj gear set to 0?

-Chris

I think the randomness of those numbers is due to the decking on the block and on the heads. His gears are true. What I'm interpreting is that's his cam settings to achieve true btdc on both banks with the machining.

[Ninja Performance]

Since we have found some adjustable cam gears to be off when set at 0, what my concern is is this:
You find how far off the cams are, or due to head milling etc using oe cam gears and he timing wheel and solid lash adjuster. So you now have those numbers. And you set those corrections onto a gear, that when at 0 it is not at 0. Therefore the settings would not be correct.

-Chris

[oohnoo]

Does it really matter if I degree'd the cams with the new cam gears and not comparing them to the oem ones. If they're off from zero, they're off. No need to go through the effort of degreeing the oem cam gears and then doing it to the aftermarket ones. As long as you do it you're good to go.

[familyMAN]

^you are correct. You are good to go since you degreed them based on your engine, cams and cam gears. If you degreed them properly and set them to "zero" that's where you are, regardless of which cam gears you have. You can keep them there until you can play with them on the dyno. No back to back testing has been done, to my knowledge, on the common +1/-3 with DR cams. I may do some virtual dyno runs at some point.

The whole bad cam gear whoopla only matters if you don't take the time to find lobe center and degree to your car.

[Italo Grasso]

Since we have found some adjustable cam gears to be off when set at 0, what my concern is is this:
You find how far off the cams are, or due to head milling etc using oe cam gears and he timing wheel and solid lash adjuster. So you now have those numbers. And you set those corrections onto a gear, that when at 0 it is not at 0. Therefore the settings would not be correct.

-Chris

Chris/Bob, Not really sure what you guys are calling "ZERO" but again 110 in/ex is NOT zero on our cars..This is what i have been trying to point out to you guys.. 110 may be the reccomended CL from whomever designed the cams..

[Italo Grasso]

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.


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)

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.

Take a look at the BC Cam Card, the note states set to "0" and then tune from there for best result, well 0 is 109.5 in/106.5 ex for us....BC could have reccomended 1XX in/ex but that wouldn't be zero (0) on our cars...Just to clear up any confusion here is the math from the BC Cam card to show the BC cam "0" is the same as our cars ((180+7+31)/2)=109 CL intake ; ((180+1+33)/2)=107 CL ex...