Ex_F-Body_Enthusiast

So, I recently purchased a 2013 Grand Sport, M6, w/ 21K miles from a TX Chevy Dealer that was a trade in for a new C7. I'm the 4th owner and I was not able to get any prior owner history on the car regarding its mods. The visual mods are: American Racing long tube headers w/ 3" X-pipe & cats, Halltech CAI w/ beehive, MSD plug wires & NPP axleback (NPP is not on the build sheet). The LS3 engine idles with a slight shake (but no real lope) compared to the wife's '07 factory LS2 which idles glass smooth. This LS3 pulls very hard above 4500 rpm, braking the tires loose at the top of 2nd gear and when shifting to 3rd at 5000 rpm the entire rear end fishtails sideways with the traction control ON (I haven't pushed it further than this yet). Since this is my first LS3, I have the following questions:

1. Does the LS3 factory cam idle as smoothly as the LS2?
2. Is there an easy way to tell whether a mild aftermarket cam is installed? (my only idea is to pull a valve cover and see whether aftermarket valve springs are installed).
3. Does the aftermarket even offer LS3 cams with near-factory idle quality?

BTW, this is the first vette I've owned since 2005, so I have a lot of catch up to do. . . but its great to be back! Any feedback would be greatly appreciated!

old motorhead

You can get anything from stock like mild to over the top wild from the aftermarket. Chevy even has an LS3 cam that's a little on the wilder side. And that one can work just fine with stock valve springs. If the manners aren't bothersome, just enjoy it!

jimijam

In just to say that Apocalypse Now is probably my favorite movies of all time. "The horror! The horror!"

coalshark

I joined up today to ask virtually the same question. Just picked up a 2012 CE Base @ 30k miles. My LS3 idles a little shaky with a variance of about +/- 50 RPM, pretty consistently but has no indicators of issues and no obvious signs pointing to an aftermarket cam. The car came with a CAI and a tune but I don't see any other mods without tearing it apart. Drives great but that idle has been nagging at me. You can really feel it with the butt sensors. Has the stock manifolds so I really doubt I have an aftermarket cam, and am leaning towards the MAF just needs a cleaning. The car pulls like a MF and drives like new otherwise.

jaybee924

What rpms is y'all cars idling at?

coalshark

Mine sits at around 510 but constantly fluctuates between 530 and 500. As if it had a very mild cam, but there's no rhythm to it.

jaybee924

That's about the right rpm range for the stock cam that I remember before I cammed mine!!!

coalshark

That's good to know. Every once in a while it will dip slightly below 500 and feel questionable but it hasn't stalled out so I'm not really worried about it. Vettes shouldn't be sitting idle anyways gotta get moving!

Ex_F-Body_Enthusiast

Mine idles between 600 - 650 rpm. Maybe a little higher than factory?

myredhead1

Hmmmmm. My pre cam LS2 idled at 500. Now, with my 224r cam (baby cam) the idle is at 650, with a noticeable shake and lope.

Craiger77

1. Yes. They should both idle about the same assuming both are stock and maintenanced well

2. Yes and no. Just by listening, a trained ear should be able to pick up if a cam is there. If It also runs hard, it definitely has a cam (and not some vacuum leak). The hard part is identifying an unknown cam. I’m guessing that’s the info you really want to know.

3. Yes. the sky is the limit on a custom cam and there are off the shelf cams that can do that too. Since you’re coming back you probably already know that you will always give up something to get the gain. The quality of the tune that goes with the cam is as critical as the cam itself in regards to drivability.