Rocker Arm>ME

BiG MiKE

BiG MiKE

Driver
Took the valve cover off tonight... And found this:
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Broken Rocker Arm
Gouges in head

Bah... Can Anyone explain this? What could have possibly caused this? How can it be prevented?

Ill post more of my findings later.. when I find the other piece of the rocker arm

:D
 
What do you mean how did it happen? They sell rocker arm stoppers for your motor for a reason. the m20b25 in the e30's has the same problem if not very similar. Hence why i swapped to a dohc with no rockers :)
 
Rockers get weak over time. Stock redtops no matter how much you nissan guys want to think were not designed for bouncing off the rev limiter or any other of the strain that drifting puts on the motor. Almost all cars that have that setup of the rocker arms break. It is usally the weak point of the head. After thousands of miles the rockers get weak and snap. Its just physics.

called you talked about diffrent head setups. Valve float why rockers suck etc etc...
 
1st off Rocker arm stoppers don't do shit

As for why that happened - chances are it needed to be re-shimmed (all of them for that matter) and was uneven (b/c there's a shim on either side of the rocker) meaning unequally distributed stress to the rocker and eventual breakage.
 
so is that head f*cked? i hope not!

So what motors were designed from factory to be bounced off the revlimiter?
 
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Guys, when you mention a revlimiter.............. its just a limit. Not a brick wall that you keep pounding. Its no different holding an engine at 7,000 or hitting a fuel or spark limiter at 7,000. (disregard engine torque produced when the physical limiter is removed, the only load on a rocker arm is the leveraged pressure of the valve spring vs cam rpm)

Cast materials in general are less prone to deformation (bending or flexing) but are brittle, which means if they do give, they break completely.

Id think loose valve lash and an expired service time are the culprits.
 
purchase new rocker arms................

Gouges in the cam cap and spark plug housing gasket area are not crucial. As long as the valve is not bent or the valve train damaged, id make sure all debris have been removed and put a new rocker in.

lol you should see some of the shit that ive seen.
 
240SicknessX said:
purchase new rocker arms................

Gouges in the cam cap and spark plug housing gasket area are not crucial. As long as the valve is not bent or the valve train damaged, id make sure all debris have been removed and put a new rocker in.
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I disagree. Replace all the rockers while you are there. They are only 30 bucks oem.
 
now now ladies go back and tuck your penises away and go back about your business.
 
e30 gangsta said:
I disagree. Replace all the rockers while you are there. They are only 30 bucks oem.
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yeah but they are a completely unnecessary $30 and they'll all still have to be shimmed properly.

Speaking of which - Mike I can link you to thread about creating a tool to properly shim the rockers if you need it. The FSM says you need some fancy pants Nissan tool but you don't if you make your own tool. Don't know if you know about it or not.
 
damn that sucks man...time for a head rebuild. some new valves/shims/springs/retainers...set that badboy up for 8500-9krpm redline? Thats if your looking to spend the money. A friend did the same thing rite when he got his coupe out of the shop with fresh paint and jdm silvia front end. ripping 3rd gear hit 2nd instead of 4th and over-reved the shit out of the motor, stock red-top sr20 and broke 2 rocker arms...his valves ended up hitting the piston and fucking shit up. Sucks it happened but it can be fixed. Good luck. :bigthumbu
 
yea i put the little shims that sit on top of the valve springs to hold up the rocker arms backwards.. so when the motor started up 2 rockers went nuts and scratched shit up in there.. but its all good they were replace, head has scratches on it in the inside and some of the titanium guides are scratched but not enough for concern... its running good now
 
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