Careful with that camshaft

[XfireZ51]

Hans,

The cam is a regrind. Its an intake cam that was installed when we first installed a set of ported heads, so its been ~ 7 years. I later added a set of exhaust cams ~ 4 yrs ago. So I have a paper trail of the incremental power each upgrade can result in.

[Pete]

I use custom made aluminum temporary cam caps i install these on all the cam journals then use a breaker bar and box wrench to break cam bolt loose.
I have taken off 100's of LT5 cam bolts this way for 20 years with no issues.

I do not have any back history on this cam.
I have been buying and accumulating cams the past 20 years so at this time i can only speculate.
Maybe small crack that got worse with time or i'm just very strong.

What ever it was i have never seen this before.

Pete

PS
Regrind has nothing to do with this break i have 3 dozen regrinds out there running for years with no issues some with really hard racing time on them especially the ones in Al's,Bobs and my ZR-1's for the past 15+ years and these are the fastest N/A pump gas ZR-1's out there.

[XfireZ51]

Yep, there’s really no telling what the critical flaw was for this particular cam. I’m relieved however that this happened on Pete’s bench and not while the motor was operating.
Any chance these were magnafluxed prior to install at Stillwater?

[Karl]

Originally Posted by Pete

I use custom made aluminum temporary cam caps i install these on all the cam journals then use a breaker bar and box wrench to break cam bolt loose.
I have taken off 100's of LT5 cam bolts this way for 20 years with no issues.

I do not have any back history on this cam.
I have been buying and accumulating cams the past 20 years so at this time i can only speculate.
Maybe small crack that got worse with time or i'm just very strong.

Pete I am way stronger than you...lol....odds are it was a bad cam. How it became bad I don't know.... You or Marc can change the cams in my Z anytime.

Holding it from the back or not won't make a difference if a billet steel camshaft is going to break or not.

[grahambehan]

Cam is chill cast iron, not steel.
No mag check at Mercury Dom.
Graham

[XfireZ51]

Originally Posted by grahambehan

Cam is chill cast iron, not steel.
No mag check at Mercury Dom.
Graham

Thx Graham.

Karl,

The inclusion of a hex head at the back end of the cams would indicate that the factory intended it to be used for some reason,
ie. torqueing the cam gear retaining bolt.
Again, we’re dealing w components that are approaching 30 year service cycle.
Frankly, I am amazed at how members of this community, Marc, Pete, Corey et al continue to evolve the performance envelope of the LT-5. That’s also a testament to the original design of the motor.

[grahambehan]

The hex is there to facilitate moving the cams so that the timing pins can be inserted, the cam bolts were tightened with no support at the rear of the cams, just the pins. The rear hex has been used to torque the bolts by virtually everyone that has set cam timing on an LT5, tho and is a common practice with very few incidents of failure. The cam snout breaking off tho is a far more common occurence.

Graham

[XfireZ51]

Here is perhaps a better view of the break if this helps.

[Karl]

Originally Posted by LGAFF

Super Brittle.... I had one snap off on the opposite end..... also seen several with snout failures

How many failed LT-5 camshafts have you come across?

[spork2367]

They are castings, they just aren't designed to sustain that kind of twisting torque load. Installing the cam gear bolt when new requires less torque than breaking one loose.