[scott70]

My current cam is a UD soild roller with 263/268 @ .050,, .417 lobe lift with 1.65 rockers. The LS is 108,ground 6 degrees advanced to 102 ICL.It degreed in at 101 3/4 ICL.My timing chain has advance and retard positions which I assume are 4 degrees either way.So if I retard it 4 degrees ,that would be 105 3/4 ICL.I wouldnt do the change until I get a baseline with the new 4.11 gears.

[sleepy]

I heard somewhere that advancing or retarding the cam just raises or lowers the RPM of the power curve. I think it is retard the cam lower the RPM for max torque. advance the cam raise the RPM of max torque. Could be the other way around though.

[ponchospidel]

it all depends on the total combo. it is one of those things that you have to try. in general advancing the cam makes more low end and retarding it makes more top end. i had the cam in my street car retarted 4 degrees it ran 10.70&60@ 125. i tried advancing it and the car would only run 10.90@ 122 with better air. so i will putting back retarted.

[TIN TIGR]

run it where it was designed..if you retard and run faster, it may need more cam..if you advance it, and run quicker, you may need less..how the cylinder heads react to the timing events is the key..

[Scott Stoneburg]

i've always ran mine 1-2* retarded, pontiacs make a ton of low end so there has never been a problem. i did a 2 week trial, advance 2*( with a degree wheel) then 2* retarded it ran the same ET but with it retarded the MPH was a little better and the 60' was slower. need the help hooking and when "street" racing you dont always have a good surface to start.

[ponchospidel]

tin tiger ?
so if the cam doesn't run best as it is designed to at the installed centerline, you should get a different on instead of making the most out of the combo you have???

[screamingchief]

I traditionally pick my cams a little "bigger" and install them on advanced ICL's as SOP.

Personally I feel it's the lesser of evils,and ends up being faster.

I would agree if a combo is running noticably better times with the cams ICL being retarded from split overlap/straight up,time to look into a slightly bigger cam installed @ SO/SU,or even a little bigger yet and installed on an advanced ICL.

A slightly larger cam on an advanced ICL will usually close the intake valve at pretty much the same point as the slightly smaller cam @ SO/SU,and the larger cam on the advanced ICL will usually make slightly more power than the smaller cam @ SO/SU,and do note that this is without radically changing the basic power curve.

So usually there is little penalty for doing that,cylinder pressures remain the same,RPM range is usually extended upwards a bit as well.

[scott70]

The cam I used last year was a UD solid flat 255/263 @.050 and had the same 108 LS,102 ICL.It ran slightly quicker with the timing chain /gear in the retard.I tried straight up and retard and that particular cam liked the retard.I guess the only way to find out is just try it.

[screamingchief]

I tried straight up and retard and that particular cam liked the retard.I guess the only way to find out is just try it.

OK,,,lets get this straight so everybody is on the same page...

Straight up is a very specific term,it does not mean "dot to dot" on the the timing gears!

Straight up is technically what is refered to as "split overlap",that is the cam is installed with no advance at all,that means for a 108° LSA cam,it is @ 108° installed intake centerline.

That would mean the exhaust centerline is also 108°.

Now if a cam has advance ground into it,this does'nt necessarily mean it's "straight-up" when it's installed "dot to dot" on the timing gears,as it can still easily be advanced depending on just how much advance was ground into the cam,it can still be advanced if the timing chain set is installed with some retard as well,as long as there is more advance ground into the cam than the chain set is retarded,the cam is still installed advanced.

If you were to install said cam "retarded" from SU/SO,it would have to have an installed intake centerline greater than 108° for it to be truly installed "retarded".

The ONLY way to know 100% for sure where you stand is to degree the cam!!!

As stated,if your making better power with a cam retarded from SU/SO,you seriously need to consider a bigger cam,as the current cam is not providing what the combo is wanting.

The clues a cam is "too small" for a given combo,tighening the lash consistently picks the combo up,retarding the cam consistently picks the combo up,more rocker ratio consistently picks the combo up,when all those have the combo consistently picking up power,you absolutely have too small a cam for your combo!

Hope that is clearer now.

[scott70]

Yes,I used the wrong wording.I meant it was installed on its intended 102 ICL which is the non advance-non retard timing gear placement.

[scott70]

i didnt want to touch it but my curiousity got the best of me and put the timing gear in the retarded position tonight.I'll try it this weekend and see what/if differences there are.Like i said,my old UD 255/263 solid flat prefered the retard position.If it doesnt like it,i might leave there for the rest of the year or switch it back.
I let my oldest son try the car last weekend.He's used to driving a 10.5 sec. car(1/8th).It was running 6.50's with me driving that day.He couldnt believe the power and the second time trial he got out of the groove and slightly over corrected as i'm watching the car now going sideways left to right.Luckily he had the smarts to get ot of it and straighten it out.After that he said that was enough excitement for one night and wouldnt drive it again.I hope i can get him back in the car.