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Discussion Starter #1
I have a problem with one of my rocker arm studs. I got my 289 rebuilt about a year ago. About 6 months after getting back together I had one of the studs break. I replaced that stud and the other day that same stud broke again. I was wondering if it was just bad luck or something could be causing the stud to break. Seems weird the same one would break twice. I dont think the push rod is too long, if that could be a cause but im not sure.

Also I have a second question. While removing the stud, I notice a crack in the stud bore, along the top and down the side about 1/4 an inch. I was wondering if the head needed to be replaced or if it can still be used or maybe repaired. These are HP heads C6OE and are hard to find.
 

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You may want to check and see if your rocker arm is running out of travel and hitting the stud.If you have a high lift cam and to long of push rods this may be possible. If you have press in studs you may want to machine them for screw in studs. That way you will have to machine the boss down and remove the crack before it goes any further. Let us know what you find.


69 Mach 1 427 Windsor
 
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Discussion Starter #3
Hi-po heads had screw-in studs from the factory, sounds like that's not what you have.
If you do decide to go with the screw-in studs, the mounting surface will need 3/16 - 1/4" milled down, so that might get you underneath that crack. Good luck.
 

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Do your heads look like this?

How does the pushrod in the offending hole look? Is it straight? Examine the rocker arm and compare to an adjacent one. The areas where the ball rides (if stock) and where the rocker contacts the valve stem are important. Examine the tip of your valve stem and note any problems.

What camshaft is running in this engine?

I had this problem in my street racing engine back in the 70's and it turned out to be due to using inexpensive replacement studs instead of Milodon's (ARP's didn't exist at the time)...also, I had a couple of rockers where the slot was impinging the stud slightly at full lift....that's when I learned to extend the slots a bit with high lift cams (couldn't afford roller rockers back then)...

Stud boss crack can be terminated and repaired by a competant shop...I'd likely drill and pin the crack end, notch and TIG weld the crack with nickel, CI or SS filler and re-tap the threads...

If your heads are not OEM hi-po, there will be more questions to ask, some of which have been hinted by others...

Check some stuff and get back to us..
 
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Discussion Starter #5
Ok, the heads are the regular 4 barrel heads with push in studs, not the OEM HPs.

Going to check the specs on the cam with the shop that rebuilt the motor on monday and ask them what could be the problem. The valve stem tip and rocker arm have no obvious marks or damage other than the normal wear in the areas of the fulcrum seat and valstem/push rod seats.

The only other information I can offer at this time, is that the break happened at the base of the threads(press in stud). The part that broke off only extends about 1/8" below the nut.
 

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Thanks for the update...FYI, if you reply to my post, I'll get a notify in e-mail....otherwise, since you replied to your own post, if I hadn't wandered back through, I'd never had seen it...

Normal for stock studs to break at or near the thread root; there's a slight stress raiser there and, since yours were OEM, they've seen more than their share of cycles...

While you're at the shop, ask them how much it would cost to convert the heads to screw in studs and guide plates (if the heads aren't slotted like in the picture I posted)...the cam specs will drive my recommendation but at least then you'll know what to expect cost-wise.

If converted, likely the machine work (spotfacing the bosses) would remove most or all of the crack. The shop can advise you further.

Personally, I don't think you have a problem....it's just old age for the studs...one got wonky, geometry went to hell and stressed the boss before the stud broke, cracking it slightly. It happens...

Get some more info and post back...
 
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Discussion Starter #7
thanks, was going to check on screw studs if the head can be fixed. Since this is the second stud to break in the same location since its rebuild (rebuilt in 2000), the only thing I can think is the push rod is too long.
 

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You can pull an adjacent pushrod to compare...if long, it's possible the rocker slot is impinging on the stud, stressing it, but you said everything looked OK so I discount that.

Other possiblites are coil bind, retainer/guide interference, valve/piston interference, bent pushrod....

Knowing the cam specs and any other work done to the heads would be helpful...update us when you can...
 
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Discussion Starter #9
I'd like to add only one thing. If you choose the screw-in stud and guide plate route, and you have slotted push rod holes, you can't run both. To solve that problem, you have the machine shop drill the push rod holes out, end of problem!
 
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I talked with the machine shop and he seems to think that the problem probably is with the rocker arm. His reasoning was since the lifters are hydrolic, if there was a problem with the cam it would affect other studs as well.

He suggested that replacing the stud and using some sealer, the engine should be able to be run without problems. But said that he could machine it for screw ins if i wanted. He said just keep an eye on the oil to see if any leaks occure. What do you think? I do belive i found a pair of 4 barrel heads like mine. Might be able to try it out and if i dont work, get the new heads redone and use those.
 
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Discussion Starter #11
talked with the machine shop. they seem to think the problem most likely is with the rocker arm. says since the lifters are hydrolic any problems with the cam would show up in other areas as well.
 

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My only concern about continuing the use of press-in studs, in that location anyway, is the crack which has formed. Unless it is stopped, the press fit will eventually give way and the stud will pop out. The heads I've done are wet (got myself into trouble one time not sealing the screw-in studs on a set of race car heads) and if a stud pops out, there will be coolant in the crankcase...

I would agree that the cam is not likely the cause...

Proceed carefully, especially if this is a daily driver...
 
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Discussion Starter #13
Im probably going to replace it with a screw in stud. I do have one question. If the crack extends down to far to be machined out, can the rest of it be repaired by welding or other means? Id hate to get stuck with the engine apart for a long time while looking for a set of 4 barrel or HP heads. I might have located a pair in good shape but if not, these can be a pain to find.
 

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Given that you're going with a screw-in stud, I'd recommend that the old stud be removed, the end of the crack drilled and pinned with the conventional method of pinning cast iron and then the boss be machined and threaded for a screw-in stud. If marking and measuring the crack end determines that the machine work will remove the entire crack, omit pinning. If the measurement shows the pin will end up with 1/2 or more of its diameter removed in the milling process, then move the pin beyond the crack end the appropriate amount. What you want is no more crack and a pin that is captured in the casting, either entirely or partial by casting and partially by the stud hex (entire capture is preferred, at least by me). I personally prefer pinning to welding but welding is an acceptable alternative if done correctly with the appropriate filler rod (usually a nickel/iron alloy). Brazing is also an option but usually puts too much heat into the casting. With either method the crack still needs to be terminated completely through the boss...
Consult your machinist for futher details...

If you have any more questions, post...

Oh, yeah, make sure they put some sealer on that screw-in stud's threads...*G*
 
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I have been looking for another set of heads in case this one cant be fixed. I got a reply from a guy saying he had a set of C6OE 4 barrel heads. He sent me some pics and they look exactly like the ones I have but I noticed the casting numbers were C6AE. I dont know the ins and outs of every ford engine, but I always heard you could tell the type of head (regular 289 vs hp heads) by the shape of valve chamber and of course the casting numbers (C6AE being regular 289 and C6OE for HP engines). Of course I know what the difference are suposed to be, but these seem to have the same shape and size vavle chambers as my C6OE heads. They seem identical, except for the casting number difference. Below is a pic.

http://www.users.ezwv.com/~gregw/289.jpg
 

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All 289 heads of this vintage are essentially similar. The HiPo heads have cast-in spring cups and screw in studs but everything else is essentially the same, including ports, chamber volumes and shapes. The picture I provided to you earlier in the thread outline the differences which denote the head as hi-po...

Look at this picture of the head you posted...note my comments.

Are your current heads the same as these?

Update when you have time...
 
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Discussion Starter #17
yes, the push rod holes on mine are not slots and the rockers I use have the guides on them for the valve stem.

If all the heads are the same(with exception to the HP) then what do the casting numbers denote. Mine are C6OE and the ones in the image are C6AE. And would there be any performance difference using the C6AE heads.
 
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PS, you said watch for sunken seats? the seat seem similar to what my current ones are. What do the sunken seats mean?
 

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Sometimes rail rockers (the kind you have) can have problems with performance camshafts...this was the type of rocker which caused stud breakage on my street racing engine years ago (it had a mild performance camshaft in it)...I didn't know enough about engines then to understand the nuances of the valvetrain system and the stresses it's under.

Sorry but I can't help you regarding the reasons for the casting number differences.....I only know the parts from their physical appearance...perhaps the restoration gurus can help you with casting numbers and their significance. I do know all the early 289 castings I've worked on are similar to the one you pictured, with the exception of a set of C3 289 castings I own, which have a chamber similar to the W heads except much smaller.
 

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Pictures can be deceiving but it appeared that the entry angle width was wider that what I consider normal for a typical valve job....usually, as a head has had more valve jobs done to it, or if a seat gets wiped out, the valve seat tends to sink as more material is removed to get a proper seat. Usually, either installing hard seats or going to a larger valve mitigates this tendancy...

If I saw a 3/4 view (angle view) of the head with a valve seated in the intake hole, I could probably give a more accurate assessment. Maybe I'm just seeing things *G*...

A sure-fire way to tell would be to install a stock length valve and measure the installed height on the spring side...I can't recall the nominal dimension but I'm sure it's in a book somewhere...likely the cam folks have that kind of info in instructions or on a web site..

Hope that helps!
 
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