LS1derfull

Any cam in 224* range?

LS1derfull

No one on this site has thought to play with cam intake centerline? Any input from testing this would be appreciated.

Tin Indian

The TR-220 cam I purchased has an LSA of 114.
The factory ground-in Intake Centerline (IC) is 110.

That gives it already 4 degrees advance if installed dot to dot. I think 4 degrees advance is more than enough, without installing an offset bushing or an adjustable crank gear and putting more advance in it than the regular 4 degrees it has built into it.

Ron,

Tin Indian

But, I understand your question.

In my case, I would actually need to install it 4 degrees retarded in order to get it "straight up" since it has 4 degrees advance already ground-in.

Would it perform better straight-up, or with 4 degrees total advance.... Don't really know.

I have heard, low rpm throttle response is better if the cam is advanced, but high rpm power is a little better with no advance.

Am I right?

wrencher

iTrader: (2)

Yes you are right + you can retard cam to get more top end. The " advance ground in" is for chain slack the only way to tell for sure is to degree in the cam with either I.C.L. or opening & closing specs @.050. Example you degree your ICL it supost to be 110& it's 108 atdc you need to advance that cam 2 degrees for it to be installed "strait up" according to cam card. The only way to know were cam is is to degree it in. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Tin Indian

wrencher [Quote]: The only way to know were cam is is to degree it in.

I agree, but at least recently, all the folks that have degree'd in various LS1 Comp Cams have all stated that they came in within 1 degree of what was stated on the cam card.

I may be lazy, but thats why I am just going to put it in dot to dot with a new single Rollmaster chain set and leave it with the ground-in 4 degrees advance it came with.

Ron,

BTW, the Thunder Racing TR-220 is wrongly advertised on there web site as 220/220 .561"/.561"

It's actually 220/220 .553"/.553"
The LSA was to be 114, but actually was measured at 113.5 on Thunder's Cam Doctor (very close and no problem for me)

<small>[ October 14, 2002, 10:57 PM: Message edited by: Kimchee and Rice ]</small>

Black Magic

The 4 degrees also helps compensate for timing chain stretch. As the chain fatigues, it'll gradually retard your timing. If anything, I'd avance the cam a degree or two. LS1's already have smokin' top end power, but kinda fall short in bottom end torque. A degree or two of advance could help enough to get the grunt you need. Nine times out of ten, I still set it dot-to-dot.

LS1derfull

Has any one out there with 224* on a 112* lsa played with ICL position and track tested to confirm perf. difference? 4* advance versus straight up? 60 ft. time difference? TIA

LS1derfull

Thanks guys, i understand the effect on paper that cam advance or retard provides, what my question is; has any one back to back tested LS1 for best track times, their cams intake centerline position?

Patrick G

iTrader: (14)

No track times, but lots of dyno time. The School of Automotive Machinists (SAM) has done extensive engine dyno testing on LS1s and has come to the following conclusion. Intake closing point is the most important determining factor for where (and how much) power the LS1 makes.

Cams that have an intake closing point of 40 degrees ABDC tend to make peak power around 6000 rpms. Close the intake around 42 degrees, they peak around 6100. 44 degrees, 6200 rpm power peak. 46 degrees, 6300 rpm power peak.

You can vary intake closing point by playing around with duration, LSA and ICL. For example:
TR 224/224 112LSA +4 cam has intake closing point of 40 degrees ABDC (6000 rpm peak).
TR 224/224 114LSA +4 cam has intake closing point of 42 degrees ABDC (6100 rpm peak)
TR 220/220 114LSA +0 cam has intake closing point of 44 degrees ABDC (6200 rpm peak)
2002 ZO6 204/218 117.5LSA -2.5 cam has intake closing point of 42 degrees ABDC (6100 rpm peak)
TR 230/224 111 LSA +2 cam has intake closing point of 44 degrees (6200 rpm peak)
MTI 209/216 116LSA +4 A1 cam has intake closing point of 36.5 degrees ABDC (5600 rpm peak)

Ideally, you want a cam that is size appropriately for an LS1 to be installed with 0 advance. For a 346, 224 duration seems to be ideal. Go bigger like to 236, you will benefit by advancing the cam. Go smaller like to 214, you will benefit by retarding the cam. The main reason is to get the intake closing point to a time where the engine can best use it. According to SAM, with a 224 cam, they lost about 5-7 rwhp and torque everywhere by advancing the cam 4 degrees and nearly the same by retarding it 4 degrees. But take a 214 cam and you will probably gain 5-7 rwhp and torque everywhere by retarding the cam 2-4 degrees. General rule of thumb. Too small a cam: retard. Too big: advance. Just right: go straight up. Not opinion, just proven dyno results by SAM.

<small>[ October 15, 2002, 07:31 PM: Message edited by: Patrick G ]</small>

LS1derfull

Thank you Patrick G, i like your informitive answer. I read a Sam article about that test you spoke of, and i was curious about track perf. difference with cam advanced because Judson tested all mods except that one at the track.Dyno is hard evidence, but my car hooked dead is in a definite stumble that tuning like this can make a dramatic difference with. I care more about proper accelleration then i do ultimate power.Even in a bog my car runs decent but im losing half a second in et in my opinion to this bog recovery. Anyone else out there test cam position for tune purposes? <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />