Rocker Stud Broken
Thread Starter
Instructor
Joined: Aug 2007
Posts: 224
Likes: 1
From: SHERMAN TEXAS
Rocker Stud Broken
After A Hard Run Home From Work Tonight My Car Started Running Rough. I Thought It Might Be A Fould Plug Until I Got Home And Saw A Ding In My Valve Cover. When I Pulled The Cover My Rocker Arm Was Laying On Its Side. Quickly I Worried Where Is My Polylock And Hoped The Set Screw Was Still In. Well I Found The Lock With The Set Screw In It And The Top Of My Stud. Has Anyone Ever Had This Happen To Them.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
It's a possibility, but I have used rollers that don't cover the whole stud.
The fact that they are screw in makes this easier for you. I would replace them with a stronger stud though as they may be a budget component and weren't up to spec to be used on the heads
Now, it could be that you have an underlying issue that caused the problem. Have you made sure that you don't have spring bind or alignment problems.
Thread Starter
Instructor
Joined: Aug 2007
Posts: 224
Likes: 1
From: SHERMAN TEXAS
Your Probly Right Im Going To Buy A Set Of Arp And Replace For A Piece Of Mind. Now That You Mention It The Shop Supplier Is A Dirt Track Community That Supplies Alot Of Cheap Off Brands. I Bet Thats It. Thanks For Opening My Eyes Db.
Thread Starter
Instructor
Joined: Aug 2007
Posts: 224
Likes: 1
From: SHERMAN TEXAS
My Rockers Sit Well On Valve Tips. Should I Still Be Worried About Length? Would Longer Pushrods Just Set The Rocker Higher On Stud And Maybe Thats Why The Polylock Doesnt Seem To Thread Down On Stud Very Far? Also Would Longer Pushrods Cause Me To Lose Lift From My Cam.
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Drifting
Joined: Aug 2005
Posts: 1,682
Likes: 3
From: League City TX
I have broken studs on completely stock engines. Sometimes it just happens.
I would check to make sure that I had adequate piston to valve clearance, retainer to guide clearance, and coil clearance when the springs are fully compressed.
Lack of clearance in any of these areas are likely to break studs.
I am assuming with poly locks you are running roller rockers, correct?
The reason I ask is stock rockers without a long enough slot can break studs too.
I would check to make sure that I had adequate piston to valve clearance, retainer to guide clearance, and coil clearance when the springs are fully compressed.
Lack of clearance in any of these areas are likely to break studs.
I am assuming with poly locks you are running roller rockers, correct?
The reason I ask is stock rockers without a long enough slot can break studs too.
Racer
Joined: Jan 2008
Posts: 291
Likes: 15
From: Virginia Beach VA
Did you check to make sure lifter didn't come out of the bore or that your oil pressure drop? I had the same thing happen to me... but I luckily had the AFR Hydra Rev Kit keeping the lifter in place.
If its a stock roller cam is the spider retainer plate enough to keep it in place?
If its a stock roller cam is the spider retainer plate enough to keep it in place?
Thread Starter
Instructor
Joined: Aug 2007
Posts: 224
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From: SHERMAN TEXAS
They Are Full Roller With Guideplates. Peeking Down I Can See The Lifter Is Still In Bore. IM THINKING IT MIGHT JUST BE A FREAK THING AND WILL BE REPLACING TUESDAY.
Last edited by colin75; Mar 23, 2008 at 09:46 PM.
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From: Corsicana, Tx
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You want as much thread engagement as possible on the studs. You want the rocker riding on the *shank* area of the stud...not the threads. You do whatever you have to with pushrods to get geometry right,..then check the current stud and see if it will work. if not,..you dig through the ARP catalog..they have many variations. The lockscrew should be slightly above the nut...not down in it.
Just for example..my 540 uses ARP studs actually designed for an obsolete Ford SVO 351 Cleveland arrangement. Ford had a deal where the studs extended up through the valve cover itself and it used the valve cover as a stud girdle. Worked well. I needed studs a little different after I worked out my pushrods etc...and found them. I had to shorten the upper threads .300"...but they fully engage the adjusters and really stiffen things up.
JIM
Just for example..my 540 uses ARP studs actually designed for an obsolete Ford SVO 351 Cleveland arrangement. Ford had a deal where the studs extended up through the valve cover itself and it used the valve cover as a stud girdle. Worked well. I needed studs a little different after I worked out my pushrods etc...and found them. I had to shorten the upper threads .300"...but they fully engage the adjusters and really stiffen things up.
JIM
Racer
Joined: Jan 2008
Posts: 291
Likes: 15
From: Virginia Beach VA
On the same note... When mine broke I was running self-aligning roller rockers with guide plates. At the time I didn't know any better. I don't think this was the cause of mine breaking... but I don't really know... maybe the side load from the guide plates and self-align rockers working against each other made thing worse.. I have since fixed the problem...
Just out of curiosity, was it your intake or exhaust stud that broke?... Mine was the intake and I've wondered what would happen if the exhaust stud broke and the charge was able to com bust but not exhaust... if the damage would have been worse...?
Thread Starter
Instructor
Joined: Aug 2007
Posts: 224
Likes: 1
From: SHERMAN TEXAS
After Extensive Felt Tipping Valves And Turning Over Motor Ive Finally Come To The Conclusion That My Pushrods Are Waaay Too Long. I Put In One Of My Old Original Pushrods After Re Applying Marker And The Roller Contact Seems Perfect. It Rolls Slightly Past Center Both Ways(with Factory P.r.) Also There Is More Rocker Arm Stud For The Polylock To Grab .. And With The P.r. That The Machine Shop Recommended The Roller Never Leaves The Outer Quadrant Of The Valve Tip. Will Be Getting New Pushrods Tomorrow. Thanks For All Help...
