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Author
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Topic: What caused this rocker arm stud to break like this???
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f100cleveland
Gearhead Posts: 328
From: St. James, MN
Registered: Sep 2004
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posted 04-26-2005 12:20 AM
   
I was adjusting valves last night with the engine not running, doing the cold adjust method. I was turning the engine over with a 1/2" ratchet and there was a loud snap from the passenger side of the engine. I couldn't see anything visible that had fallen or broke, but I had that side adjusted and had the valve cover back on all ready. Well, I went to start it up and there was a loud clicking noise from inside the passenger valve cover. I pulled it off and the rockerarm fell out as soon as I lifted up the cover. The adjusting nut was still attached to the stud and the bottom hex of the stud is still on it too. The rocker stud broke off right where it goes into the head. I just put these rocker studs in about 3 weeks ago and they only have about 50 miles on them so far. But why did it break under the hex head and I can't turn the broken piece of the stud out? There is only about 1/8" or so sticking up above the head rocker pedastal. I'm confused on why this happened or what would've caused it. Why did it happen when the engine was off and I was turning it over by hand and not when it was running?
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1982 Ford F100 2wd Shortbox. Powered by a 357 Cleveland w/ closed chamber 4v's and a Funnelweb. Full Roller c-6 trans with Gear Vendors Overdrive and 4.86 geared Detroit Locker equipped 9" rear. 1982 F100 351c 4v 1977 F150 460 Burnout Truck
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Moneymaker
Administrator Posts: 26513
From: Lyons, IL, USA
Registered: May 99
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posted 04-26-2005 01:10 AM
Just a guess here, but it sure looks as if the stud may have bottomed out in the head causing the threads to bind up.------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
NHRA and IHRA SS/LA & SS/MA National Record Holder '00,'01,'02,'03,'04 &'05
First NHRA & IHRA 289 automatic Superstock Mustang in the TENS 06-99
First SS/MA in the TENS 04-03
IHRA division 5 Superstock Champion
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28 The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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clevelandstyle
Gearhead Posts: 1098
From: Connersville, IN
Registered: Jul 2001
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posted 04-26-2005 07:49 AM
I agree. If you have 1/8" of thread sticking out of the boss, that means the thread was bottomed out before the shoulder.------------------
Ben
Grabber Green '70 Mach I 351C 4V
Robbin Egg Blue '79 Fairmont 408C 4V, 10.50 127 MPH
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f100cleveland
Gearhead Posts: 328
From: St. James, MN
Registered: Sep 2004
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posted 04-26-2005 09:55 AM
I forgot to mention two things: The reason why there is an 1/8" or so is because that is the thickness of the guideplate. And also, the brand of the stud is BRODIX.------------------
1982 Ford F100 2wd Shortbox. Powered by a 357 Cleveland w/ closed chamber 4v's and a Funnelweb. Full Roller c-6 trans with Gear Vendors Overdrive and 4.86 geared Detroit Locker equipped 9" rear. 1982 F100 351c 4v 1977 F150 460 Burnout Truck
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Hans olsson
Gearhead Posts: 670
From: Sweden
Registered: Apr 2000
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posted 04-26-2005 04:36 PM
How much clearance do you have in the spring at full lift?If there is no interference anywhere in the valve train maybe just a bad stud. ------------------
- VIN 1F05M139343
- 71 Mach 1 Ram-Air
- 351C 4V 285 HP
- F-G/Stock Aut
- Stockers are way cool!
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Moneymaker
Administrator Posts: 26513
From: Lyons, IL, USA
Registered: May 99
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posted 04-26-2005 05:38 PM
quote:
Originally posted by f100cleveland:
The reason why there is an 1/8" or so is because that is the thickness of the guideplate.
I took that into consideration.
Studs may be junk also.
I have no idea who makes the studs for Brodix.
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Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
NHRA and IHRA SS/LA & SS/MA National Record Holder '00,'01,'02,'03,'04 &'05
First NHRA & IHRA 289 automatic Superstock Mustang in the TENS 06-99
First SS/MA in the TENS 04-03
IHRA division 5 Superstock Champion
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28 The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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grego37
Gearhead Posts: 266
From: los angeles,CA,USA
Registered: May 2004
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posted 04-26-2005 06:27 PM
Just a guess
You said you just had just adjusted that side.
Is there a chance you adjusted this particular valve when you shouldnt have?Help me guys, but If he adjusted the valve when he wasn't supposed to, then rotated the motor over, could this cause something to bend or break ? Which meathod of valve adjusting are you using? Id check your pushrods for straightness especially on that rocker.
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Moneymaker
Administrator Posts: 26513
From: Lyons, IL, USA
Registered: May 99
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posted 04-26-2005 08:50 PM
Inferior quality studs will break if the allen screw jam nut is over tightened against the poly lock causing stress on the fine threads.
I imagine that this is possible on the clylinder head side also with the coarse threads.------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
NHRA and IHRA SS/LA & SS/MA National Record Holder '00,'01,'02,'03,'04 &'05
First NHRA & IHRA 289 automatic Superstock Mustang in the TENS 06-99
First SS/MA in the TENS 04-03
IHRA division 5 Superstock Champion
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28 The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
IP: Logged |
f100cleveland
Gearhead Posts: 328
From: St. James, MN
Registered: Sep 2004
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posted 04-26-2005 11:52 PM
FOUND THE PROBLEM!!!!!!
After getting the old stud out tonight, we noticed that the radius that goes up against the flanged area bottoms out on the top of the tapped hole. It marks up the radius cut about 3/4 the way around. My rocker stud doesn't quite make contact with the guideplate before the radius makes contact with the top of the hole. There is about a 0.010" gap between the rocker stud flange and the guideplate. So, now I need to find some super small shims that fit under the rocker studs to get the radius off the pedestal or chamfer the holes a little bit. I am going to replace all the studs though.------------------
1982 Ford F100 2wd Shortbox. Powered by a 357 Cleveland w/ closed chamber 4v's and a Funnelweb. Full Roller c-6 trans with Gear Vendors Overdrive and 4.86 geared Detroit Locker equipped 9" rear. 1982 F100 351c 4v 1977 F150 460 Burnout Truck
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kid vishus
Gearhead Posts: 6220
From: middle of NC
Registered: Oct 2000
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posted 04-28-2005 08:12 AM
quote:
Originally posted by f100cleveland:
So, now I need to find some super small shims that fit under the rocker studs to get the radius off the pedestal or chamfer the holes a little bit.
I wouldn't be too concerned about the shims being 'super small'. Depending on where the rocker is riding on your stud, it might need a thick washer to get the rocker down where it is supposed to be. One set of C heads I had converted to screw in studs needed thick hardened washers under them to get the rockers to stop riding on the threads of the stud. The shop that converted them for me has since stopped using the method described in all literature to convert them, and now just mills off the step and that leaves the pedastal taller. They found most of the C heads they were doing the "correct" way all had the same problem as mine.
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SteveLaRiviere
Administrator Posts: 43791
From: Saco, Maine
Registered: May 99
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posted 04-28-2005 09:25 AM
Good machine shop practice always dictates tapering the edge of a tapped hole, or clearing/counterboring the first couple threads, to prevent material from pulling up during torqing. That's like Machine Tool 101 stuff.------------------
'70 Mustang Mach 1 351C 4V/FMX/3.25 Open
'70 Mustang Convertible 250 I6/3 speed/2.79 Open
'72 Mustang Sprint Hardtop 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
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