Quote:
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.
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That is why I never use hardened push rods. I use the weaker stock push rods as a safety device. Anything goes wrong i would rather bend a weak push rod than bend a valve.
Quote:
Originally Posted by Camarowguy
When the engine failed, did it suddenly stop or die and still rotate a bit?
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An engine never just stops when things are rotating at thousands of revolutions per minute.
Quote:
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.
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I conquer.
Quote:
Originally Posted by S-eatin-grin
when the pin sheared wouldn't the cam go out of time (can see on the pics that the cam was turning against the surface where the pin was) and wouldn't that cause a lifter to stick or jam?? Ultimately it seems that whatever caused the pin to sheer is what caused the failure. We are all back yard garage theorist in here (most more experienced than me). Suprised there havn't been performance shops commenting in this thread?
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I'm thinking it all started with the cam bolt. I'm guessing the bolt might have not been torqued correctly, not used lock tight or something like that. Once it doesn't have the correct torque holding the cam and gear together it is only a matter of time.