96lt1ss

iTrader: (4)

My car was missing today and making a loud valvetrain noise, so I shut it off. I checked the rocker arms and #8 cylinder intake rocker broke in half and was riding on titanium retainer. I was not beating on it at the time. WHats causes this and has it happened to anyone else?

brad8266

iTrader: (23)

They lose the needle bearings after time, its like luck of the draw. Once all the needle bearings fall out and you run it with no bearings it will get very noisy and eventually fall apart. Its happened to me before, not much of a big deal, just replace it with another one. I got one if you want it, just pay the cost of shipping.

MrEddie

So with needle bearings floating around in the oil, I assume this would require pulling the motor and possibly a rebuild? Are there any aftermarket rockers that use something other than needle bearings? THx!

brad8266

iTrader: (23)

No rebuild required, the bearings will fall down the valley and sit on the magnetic oil drain plug. Its a fairly common thing with these rockers and really is not a big deal.

96lt1ss

iTrader: (4)

It didnt lose the needle bearings. ABout a half inch of the rocker broke off almost resulting in the rocker arm hitting the retainer and dropping a valve.

brad8266

iTrader: (23)

How would a broken rocker cause the valve to drop? The spring has to break for a valve to drop.

Just replace the rocker arm.

96lt1ss

iTrader: (4)

Because it happened to a buddys car. Very simple actually: Tip of rocker arm breaks, the rocker arm comes down after tip breaks and all it can reach when the engine is turning is the side of the retainer, it then pushes the retainer down and knocks the locks lose and drops a valve.

Im wanting to know what causes this?

KCS

iTrader: (20)

How big of a cam is in his car? Specifically lift.

96lt1ss

iTrader: (4)

578/588 with 650 lift crane dual springs.

KCS

iTrader: (20)

Thanks

96lt1ss

iTrader: (4)

Any ideas?

brad8266

iTrader: (23)

Replace the rocker and change the oil.

That retainer scenario is not common at all and if your locks are still intact then you are fine.

heavymetals

iTrader: (3)

Pushing down on just the retainer might have bent the valve.

Suprised it didn't spit out the keeper parts and really mess stuff up.

I bet that retainer is chewed up.

Your lucky if that is all that happened is a broken rocker.

vettenuts

iTrader: (4)

Post some photo's. Likely fatigue from an overstress condition, which could be the result of valve float for example. How did you shim the Cranes? They have very low seat loads without shims.

96lt1ss

iTrader: (4)

Just used titanium seats. I have installed 3 sets of these springs and never anything like this.

GuitsBoy

iTrader: (4)

Wow, you rarely head about the rocker body breaking. its always the bearings. Anyway, replace and go, hopefully theres no other issues.

96lt1ss

iTrader: (4)

WHats the correct way to install the crane duals? As far as how do you know to shim or not?

vettenuts

iTrader: (4)

They set up at (from memory) 112# on the seat at an installed height of 1.800. The Crane seat will decrease the installed height to around 1.77". Without shims, mine set up at 122# on the seat, too low in my opinion for an aftermarket cam. A 0.060" shim would put you in the neighborhood of 140 on the seat, a better value in my opinion.