[Huggerorange73]

Originally Posted by mercedestech

That pin isn't supposed to see any stress at all. It is merely there as a locating pin when installing the gear. The bolt is supposed to hold everything together. I know it seems like a crappy design, but even Mercedes uses it in their 6.3L AMG engines. Infact the Benz engine doesn't even have a pin, we have a special tool that lines everthing up (cam, cam sprocket, chain, etc) while we tighten everything down. Now mind you these are overhead cams with no pushrods etc, but still a very similar design as far as the holding the cam sprocket to the cam (the Benz cam has an adjuster for cam timing not just a sprocket, but very simialr). You guys probably don't care, but I just thought I would throw it out there that a very advanced high horsepower engine made by Mercedes uses a very similar techniquie to hold everything together....and I've never seen one fail. I'll apologize now for getting off the main topic, I just want to know why this keeps destroying LS3 engines. This thread bothered me so much I just sold my TSP cam. I'm going to hold off on a cam until we know why this is happening and I'm closer to being out of warranty......It would take me months to recover from a failure like this without resorting to charging up the plastic! I'm all about paying to play, but damn......this would suck no matter how much money you have in the bank!

Great info!!!!! You should keep the cam though!

Originally Posted by Russell James

I'd bet the lifter, PR's, valves, pistons, rods, block.... all that stuff was victims after the cam gear turned. When a piston hits something solid at that RPM, especially with stronger than stock PR's, it can easily blast a lifter right through the block.

I think the question is why did the pin shear? Was the bolt shoulder bottomed out on the pin instead of gear. That bolt/gear/cam needs to be held in by 360 degrees of that bolt shoulder. If one side is cocked by the pin - the gear is going to be unstable. Pin could be too long, hole in cam not deep enough...

If no defect in the pin/bolt mounting, my next guess and I think most probable is harmonics beat up the dowel pin until it failed. The stock set up was engineered to run for days at 6600 rpm, full load, no bad harmonics. Now, change multiple things in the valve train, valve springs, PR's, cam lobe profile, balancer, raise the limiter.... will it still have no harmonics beating up the timing chain? That entire combo would have to be Spintron tested to know. Did Comp Cams Spintron that cam, those springs, PRs, balancer... and see no bad harmonics at 6800 RPM?

I'd call Comp Cams and see what they say.

Let me know what you find out....I'll be calling Comp on Monday as well.

Originally Posted by Camarowguy

When the engine failed, did it suddenly stop or die and still rotate a bit?

It didn't just suddenly stop....something let loose and then it tore itself apart.

Originally Posted by mercedestech

Just curious...was the cam bolt extremely loose when you took it off, or still pretty tight?

It was tight....had to use a breaker bar to get it loose.

Originally Posted by 2010 SS RS

Its not like it siezed up and locked. When an output shaft breaks it is clean like a broke glass rod. Then everything still works including the transmission but there is no power out of it to the driveshaft. A hard launch transfers much more shock back thru the system than when the output shaft breaks. I know you somehow want to pin this back on the shaft failure but it just holds no water or logic. Go bust your output shaft and tell me how violent of a shock it is to your engine... It just is not. just sayin.

Makes sense!

Originally Posted by Camarowguy

Maybe the bolt did come loose and make the pin break. So maybe the shop should eat it. Was the bolt loose? I never saw an answer back on that question.

Sorry....I just got to a PC to answer the questions. The bolt is a torque to yield....a new bolt was used.