busted rocker arm, wtf happened?
Thread Starter
12 Second Club
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From: Cooper City, FL
busted rocker arm, wtf happened? I had my heads put on approx. 3k miles ago and week or so ago **** started rattling, no power, etc. took off the valve cover tonight and found out that the bolt that goes right thru the rocker snapped off, and the little rod that connects the intake and exhaust rocker together was also sheared off...and the ring inside the rocker is cracked...wtf caused this? it happened out of no where and I wasn't beating on it...just started it up in the parking lot.
heres some included pictures...can anyone tell me wtf happened?
also do I have to buy a whole new set of rocker arms? or can i replace just 1 or 2?
so guys im doing a
about this.
theres the pics...you can see how the screw was hitting the valve cover.
Chad
heres some included pictures...can anyone tell me wtf happened?
also do I have to buy a whole new set of rocker arms? or can i replace just 1 or 2?
so guys im doing a
about this.theres the pics...you can see how the screw was hitting the valve cover.
Chad
What rockers are those? Looks like the rocker bolt broke and caused all the other damage. Where did you get your bolts? Hardened bolts shouldnt break like that. Guessing here but it looks like those bolts came with the rockers. If so contact who ever made the rockers for warranty info. Defective material. It takes 22 ft lbs of torque, certainly not enough to shear that bolt like that.
Thread Starter
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From: Cooper City, FL
I didn't install them btw...
so do I have to buy a whole new set or rocker arms?
Chad
HS should replace it for free. Call them I'm sure they'll have you send them the bolt and rockers and they'll know if anyone has ever had trouble.
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Thread Starter
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From: Cooper City, FL
Normally I might agree with you but we're talking about 22 ft lbs and a brainless install. You torque them down and thats it. There, in my mind, is no way the installlation is at fault as there is no real way to screw it up unless the pushrod length was way off being to long and they weren't sitting flat. Bolts can be defective like anything else. All is takes is an air bubble. Look at how clean the bolt sheared and right at the beiginning thread line. The head is aluminum I doubt it can be over torqued without stripping the boss. Its a 8mm bolt. It doesnt break that easy unless there was something wrong with it.
HS should replace it for free. Call them I'm sure they'll have you send them the bolt and rockers and they'll know if anyone has ever had trouble.
HS should replace it for free. Call them I'm sure they'll have you send them the bolt and rockers and they'll know if anyone has ever had trouble.
Chad
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Looks like a geometry issue to me. Did you check:
1. Wipe
2. Distance to coil bind distance
3. Retainer to seal distance
4. Interference with retainer and pushrod through entire valve motion on both intake and exhaust
5. Pushrod length
6. Installed height
1. Wipe
2. Distance to coil bind distance
3. Retainer to seal distance
4. Interference with retainer and pushrod through entire valve motion on both intake and exhaust
5. Pushrod length
6. Installed height
If you would read the thread you can clearly see he didnt do the install. Dart heads, what size pusrods? Only way this is a geometry issue is if the pushrods are too long and then why isn't there an issue with the rest of them. It is possible the mech didnt get the rocker secured properly.. yes but unlikely. Even at full lift you can sink the bolts completely and sit flat. They're hydraulic (lifters) they just compress.
Now to back your theory I'd ask if the rocker came with shims as well? The YT's do and you need to use the shims. If who ever did the work left off the shims then it is possible to have a geometry issue. But why would you leave shims out? You get a kit you install it, all the parts not just some so I am assuming the job was done correctly as far as that goes.
So if shims were left out then you have an issue with more than one rocker. Only one broken bolt here so......
Take and look at the remaining rockers. See if there is any play in them. If they are sitting flat on the pedestal or if there is a slight gap somewhere.
What size pusrods and were the heads shaved at all? Was locktite used?
As suggested check the remaining bolts to see if they're tight. If you have a torque wrench then use it and see whats up. If some are loose then you know what happened.
Now to back your theory I'd ask if the rocker came with shims as well? The YT's do and you need to use the shims. If who ever did the work left off the shims then it is possible to have a geometry issue. But why would you leave shims out? You get a kit you install it, all the parts not just some so I am assuming the job was done correctly as far as that goes.
So if shims were left out then you have an issue with more than one rocker. Only one broken bolt here so......
Take and look at the remaining rockers. See if there is any play in them. If they are sitting flat on the pedestal or if there is a slight gap somewhere.
What size pusrods and were the heads shaved at all? Was locktite used?
As suggested check the remaining bolts to see if they're tight. If you have a torque wrench then use it and see whats up. If some are loose then you know what happened.
TECH Fanatic
Joined: Jun 2002
Posts: 1,979
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From: Upstate NY
Just for my information, how were the "top hat" spacers installed under the rocker arms? Big end ("brim")down or big end near the rocker. I ask because I couldn't find installation instructions online and I can't determine from the pictures.
It appears that the bolt failed from bending loads, not tension. If the top hat brim was against the head, the top hat would take most of the bending loads and the bolt would be used as a clamping device, as it should be. If the top hat were reversed with the brim at the rocker the bolt would be forced to take the bending loads which is a bad idea. It's only 8mm (.315 in.) which means the max area is only about 52% of the area of a 7/16 stud or 71% of a 3/8 stud as used in SBC heads. Bending strength depends a lot on cross-sectional area of the stud/bolt.
Perhaps I don't understand the Sharp design. It wouldn't be the first time that occurred.
I, too suggest discussing the failure directly with the manufacturer. The rest of us are just guessing.
My $.02
It appears that the bolt failed from bending loads, not tension. If the top hat brim was against the head, the top hat would take most of the bending loads and the bolt would be used as a clamping device, as it should be. If the top hat were reversed with the brim at the rocker the bolt would be forced to take the bending loads which is a bad idea. It's only 8mm (.315 in.) which means the max area is only about 52% of the area of a 7/16 stud or 71% of a 3/8 stud as used in SBC heads. Bending strength depends a lot on cross-sectional area of the stud/bolt.
Perhaps I don't understand the Sharp design. It wouldn't be the first time that occurred.
I, too suggest discussing the failure directly with the manufacturer. The rest of us are just guessing.
My $.02
Old stroker with the YT's the pedestal is notched on one side and impossible to install wrong. It fits up into the trunion area in only one way. Not sure about the HS' but they look the same pretty much. Looking at the pics it looks like the HS pedestals are completely round. I agree it looks like it was sheared and not stretch. Clean break which indicates bent or defect. Kind of fun to guess online what happened with limited info. Will be interestting to see how it goes with HS. Keep us posted.
you cant really overtorque the rockers anyway...the head is aluminum, so you would pull the threads from the head, and once you hit the 22ft/lb, the bolt just doesnt really turn anymore anyway.
i vote for bad batch
i vote for bad batch
Thread Starter
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From: Cooper City, FL
thanks for replies.
the pushrods are 7.400
I wouldn't think its geometry related as I have been driving the car close to 3k miles since the install, wouldn't that happen almost instantly?
And I dont know how to check
1. Wipe
2. Distance to coil bind distance
3. Retainer to seal distance
4. Interference with retainer and pushrod through entire valve motion on both intake and exhaust
5. Pushrod length
6. Installed height
sorry but i'm just learning guys...
Chad
the pushrods are 7.400
I wouldn't think its geometry related as I have been driving the car close to 3k miles since the install, wouldn't that happen almost instantly?
And I dont know how to check
1. Wipe
2. Distance to coil bind distance
3. Retainer to seal distance
4. Interference with retainer and pushrod through entire valve motion on both intake and exhaust
5. Pushrod length
6. Installed height
sorry but i'm just learning guys...
Chad
Wipe is easy.
Take the rocker off and paint the top of the valve stem. I used a sharpie. Then put it back together and turn the engine over by hand a few times. Then take the rocker back off and look at the valve stem. You should see a wear pattern in the paint. It should be centered. If it's off to one side be it front or back then you have a geometry issue. 2,3 from above and 6 dont matter here. Its pushrod length.
Take the rocker off and paint the top of the valve stem. I used a sharpie. Then put it back together and turn the engine over by hand a few times. Then take the rocker back off and look at the valve stem. You should see a wear pattern in the paint. It should be centered. If it's off to one side be it front or back then you have a geometry issue. 2,3 from above and 6 dont matter here. Its pushrod length.
TECH Enthusiast
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2 is easy. just run the valve to full lift and use a feeler to chck it. You are going to have to move fast as the lifter is going to bleed down.
3 is not so easy. It would require removing the spring and running the retainer to the stem.
I also doubt that would be the problem. Seems unlikely. I could belive spring coil bind though or some other valve train control issue.
Do you have the specs on the camshaft ? what ratio are those rockers ?
3 is not so easy. It would require removing the spring and running the retainer to the stem.
I also doubt that would be the problem. Seems unlikely. I could belive spring coil bind though or some other valve train control issue.
Do you have the specs on the camshaft ? what ratio are those rockers ?
thanks for replies.
the pushrods are 7.400
I wouldn't think its geometry related as I have been driving the car close to 3k miles since the install, wouldn't that happen almost instantly?
And I dont know how to check
1. Wipe
2. Distance to coil bind distance
3. Retainer to seal distance
4. Interference with retainer and pushrod through entire valve motion on both intake and exhaust
5. Pushrod length
6. Installed height
sorry but i'm just learning guys...
Chad
the pushrods are 7.400
I wouldn't think its geometry related as I have been driving the car close to 3k miles since the install, wouldn't that happen almost instantly?
And I dont know how to check
1. Wipe
2. Distance to coil bind distance
3. Retainer to seal distance
4. Interference with retainer and pushrod through entire valve motion on both intake and exhaust
5. Pushrod length
6. Installed height
sorry but i'm just learning guys...
Chad
