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

[Italo Grasso]

I actually did some testing as well and found that with larger duration cams, big turbos, large exhaust 0 is the best place..I could see lower boost big exhaust being benificial with scaveging effects but big turbos at high boost increase the intake vs exhaust pressure ratio (also have to consdier turbine and turbine housing retrictions) and cause reversion. My thoughts are that with an intake to exhaust pressure ration of 1 or less overlap is ok but with higher ratios you will mot evacuate all the burnt mixture. Wish we had cam phasing to bennifit from low boost overlap and then spread them out at hight boost..i guess youu have to find a happy medium and just go with it..

[Italo Grasso]

I just finished doing mine and all were set without touching the degree wheel, once it's set you don't do anything. Sure you're using cylinder #4? This is the middle rear one.

Anyways just to update. I got the cam sheet from Matt for my DR Street cams and after speaking with Ray he said to degree them using the lobe center which was 110°. Results for adjusting them are as follows:
#1 Intake = +.4°
#1 Exhaust = +1
#4 Intake = -.1
#4 Exhaust = -.5

Hey Oohnoo, interesting that you set the in and ex at 110 with more lobe seperation...I believe you actually spread them out further than stock (109.5 in, 106.5 ex)...

[oohnoo]

Hope I got it right. I think what happened here is the cams were not in spec. The cam sheet spec'd both intake and exhaust to 110°
I may have farked up as I never did this before. Care to help?

Hey Oohnoo, interesting that you set the in and ex at 110 with more lobe seperation...I believe you actually spread them out further than stock (109.5 in, 106.5 ex)...

[Italo Grasso]

Hope I got it right. I think what happened here is the cams were not in spec. The cam sheet spec'd both intake and exhaust to 110°
I may have farked up as I never did this before. Care to help?

Well, you can put the cam CL's where ever you like but from chris's post most like +1, -3 from the stock CL and i believe you have done the opposite..Instead of increasing overlap you spread the CL's out further than stock (smoother idle)..Chris, is this right?

[Ninja Performance]

Overlap, from what I gather, helps in a FI setup as it ensures complete (or more complete) combustion/exhaust evacuation for a better cleaner air/fuel charge. The out going gasses help pull thru the new charge as the new charge help push out the old.

-Chris

[Italo Grasso]

Overlap, from what I gather, helps in a FI setup as it ensures complete (or more complete) combustion/exhaust evacuation for a better cleaner air/fuel charge. The out going gasses help pull thru the new charge as the new charge help push out the old.

-Chris

Correct Scavaging does help evacuation but in terms of our CL's for +1, -3 Oohnoo should have put his CL's at 107.5 in, 100.5 ex to optimize the cams right?

[oohnoo]

Think I set mine currently at zero and was going to have Ray tune them from there, I'll have to check my notes. These are DR street cams and were way off.

[Italo Grasso]

Think I set mine currently at zero and was going to have Ray tune them from there, I'll have to check my notes. These are DR street cams and were way off.

Well, if you don't mind me asking what is zero for you?

[oohnoo]

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

Well, if you don't mind me asking what is zero for you?

[Italo Grasso]

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

I guess I missunderstood, i see your cam gears adjustments but that really doesn't tell me much in terms of in/ex CL only tells me you had to compensate for given head/block decking and cam grinding offsets....What i'm saying is the stock CL's for our cars is 109.5 in/106.5ex so that is zero, if you put them at 110 they are further seperated then stock and lastly if you put them at +1, -3 then they should be 107.5 in/100.5 ex. For some reason no one is willing to confirm these numbers which is odd to me...