Ruined cam - how?

[farmtruc]

Hey guys, I have this camaro in the shop (from another local speed shop) and it was backfiring out the intake. Well, we immediately checked the rockers and found out one of the exhaust rockers not moving, got it nailed down to a broken lifter/roller.
It ruined the intake too, burned that runner up where it meets the head and burned the injector tip off.

We pulled the cam and all lifters for inspection and how does this happen?
All the lifters have some sort of damage or pitting to them, some of the lifter lobes are ground pretty good (see pics).

Cam bearings look fine.

[RedHeartbeat]

reground camshaft? Looks like the broken lifter may have turned in its holder/guide. Once a piece of metal gets into the air inside the engine then it keeps bouncing around until its pulverized into nothing.

[tanz45]

Bad cam bearings?

[Madd Maxx]

Coil bind or excessive spring pressure can cause that type of failure.

[farmtruc]

Coil bind or excessive spring pressure can cause that type of failure.

We replaced the lifter plastic guides too, just in case.

From the markings on the back, I can see it's a Torquer II cam, and it appears to have Patriot double springs, combination sounds about right.

We're installing an LS6 cam and new lifters for now, keeping the P springs.

I thought about excessive spring pressure as well, I thought about changing in the springs to a 918 or LS6 spring.

[carfreak07]

sure looks like some coil bind and lack of oil. What springs were on the heads? Just looks like there wasnt any lubrication and caused the lifter to turn sideways resulting in the roller breaking off. It is weird that all the rollers have some damage.......that is what leads me to believe it is a lubrication issue. Are the valves/pistons ok........maybe clearance issue?

Could be like RED said.....regrind cam....along with incorrect pushrods and coil binding. Let us know what you determine!

[GasGuzzler]

The stock cams do that too.....usually higher mileage but I replaced the cam in a GMT900 2007 6.0 3/4 truck with less than 40K miles on it a few weeks ago. Looked just like that on ONE lobe only. My theory is improper heat treat. After the lobe wears down with a channel, the roller supports on the side of the bottom of the lifter start contacting the lobe. That in turn breaks the lifter.

[ff_jeff]

What about pre-install damage? Like stuff got dropped. Or maybe wrong part was put in. Or stuff didnt get torqued down right.

[GasGuzzler]

Possibly. Dropped? I think anyone should spin the shaft in the bearings before reinstalling the chain and gears. That would tell if it was tweaked. I thought Allen said the valvetrain seemed to be adjusted properly....yet the pushrod (not the rods David...LOL) was loose on the E valve on that cylinder.

[ff_jeff]

Possibly. Dropped? I think anyone should spin the shaft in the bearings before reinstalling the chain and gears. That would tell if it was tweaked. I thought Allen said the valvetrain seemed to be adjusted properly....yet the pushrod (not the rods David...LOL) was loose on the E valve on that cylinder.

Maybe push rods were the wrong size. Looks like the lobes on the cam have a lot of wear.