Cylinder head has stripped stud. Need advice.

Neil Mylar LakewoodCA

Neil Mylar LakewoodCA

Well-known member
I recently installed a Model C cylinder head on my engine. I was retorquing the studs for the third time when one of the studs stripped.

Unfortunately I will need to remove the head, drill out the stud hole and put in an ez-out. Then retorque all over again.

The cylinder head gasket that I am using is the best cylinder head gasket.

Can I reuse it or do I need to get another?

Thanks,
Neil
 
Did you install new studs along with the new head? If the stud is just stripped and not broken, you should be able to try vice grips or something like them to get that single stud out. Have you tried that yet?
 
If the threads are just stripped try getting it out with a pair of vise grips. If it snapped and is below the head you could try a reverse rotation drill bit and ez-out if it's not broken too deep. I'd try reusing the gasket with lots of copper coat.
 
I presume that the part of the stud that is stripped is the upper threads, right? If so, there are a number of ways to get the stud out, including vice grips as suggested, a stud puller (I’ve had the best luck with the eccentric type, not the jaw type, although others may have a different viewpoint), or welding a nut down low to the stud. The advantage to the latter is that you’ll put the stud through an expansion-contraction cycle, which may help break it loose. In any of these you can try without removing the head, but if unsuccessful off the head must come.

If you are saying that the block is stripped, different matter. You would need to install some sort of insert like a Time Sert or Helicoil. Use a jig or drill the hole with the head installed, without it’s real easy to get your drill canted and make it very difficult to get the head on/off a tilted stud.

As far as reusing the gasket - no reason to not try, especially if you get the stud out without pulling the head. If you do pull the head, the cost of a new gasket (what, $40-$50 or so?) compared against the hassle of pulling the head again if it doesn’t seal would seem to me to favor replacing it with new regardless.

You say you are using a Best gasket. I’ve never removed a Best graphite gasket without destroying it.

In my experience old head bolts are so heat hardened that they are very difficult to drill out with conventional drill bits.
 
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As a last resort I used these guys to get a broken stud out, www.brokentap.com, (714) 836-6824. They use an edm (electrostatic discharge machine, at least the is what I think it stands for) to get the stud out. The bare block was not installed in the car so I could take it to them. Worked great.

Charlie Stephens
 
If the thread in the block is stripped, you won't need an easy out. It will pull out quite easily. What you will need is a helicoil or recoil insert (or something similar). The process is drill out the stripped hole with the drill provided in the kit, tap the hole with the tap provided. You MUST be careful here to keep the tap square to the top of the block. Once the hole is tapped, screw in the coil with the tool provided, break off the piece that the tool uses to screw it in, then put in your stud.
Will it hold? Heck yeh.
 
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Remove the stud with vice grips or a stud removing tool as suggested. Get the Helicoil kit with the drill and tap and drill out the hole with the head still attached. That will assure that the hole is in the right place and straight. You don't have to drill too deep, just enough to locate and orient the hole. A slightly larger hole in the head will not matter. Get the Helicoils that are long enough.

Then remove the head and clean up the block and head. Finish drilling out the hole and tap it and install the Helicoil. Do not drill into the coolant passage. Install a new stud. Do not torque the stud into the block, just a little more than finger tight. Use some gasket sealer on the stud in case the drill went into the coolant passage. Make sure to vacuum up or blow out all chips from the drilling.

Install a new gasket with the copper coat gasket sealant. Install the head and torque as usual.

Engines used in racing have Helicoil inserts in all the threaded holes in the block. The Helicoils are stronger than just the threads in the cast iron because they are a slightly larger OD size and are spring steel. If you decide to do that, use an old head as a guide and use two studs at the ends to locate the head when you do the drilling and tapping. To do the last two holes, install studs at other locations to locate the old head and then drill and tap the last two holes.

Inserts larger than Helicoils raise the possibility of breaking into the cooling passages and have a chance of causing a crack in the block.
 
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Neil Mylar LakewoodCA said:
Is there any chance that I might not need an e-z out?
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I have never had a lot of luck with E-Z outs. My best luck has been to use the head as the alignment guide, prepare a bushing that fits the clearance hole in the head with perhaps a 1/4" hole for a drill that size. Then drill a "pilot" hole in the broken stud. Then set aside the bushing and using the pilot hole sequentially increase the size of the hole by going up through the drill sizes.

About now one wishes he had a set of "left-handed" drill bits since the action of those would be one of "turning out" the stud.

As one approaches the "root diameter" of the broken piece, start checking if you can pull out "spirals" of the thread. A letter size drill set alongside decimal allows you to approach the root thread diameter "slowly." Metric drills similar.

More than likely the heat of drilling will loosen and possibly break the bond between thread and block.

I think by this method I've only gotten up to the root diameter once. USUALLY something gives before then. Chase the thread with a bottoming tap but be careful not to "break through" into the water jacket in whatever you do.

Some stud weld onto the broken stub and use this to turn out the piece. Again heat is the key. I have not done this so I'll let someone else describe this.

Joe K
 
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Neil Mylar LakewoodCA said:
When I torqued stud number 7, the reading dropped from 55 pounds to 30 pounds. I'm thinking that the threads in the block are stripped.
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Ah, this makes sense, not uncommon (my engine has at least two head holes with inserts). I have never seen a stud that had stripped, only the block. See what Synchro909 wrote in #8 and what nkaminar wrote in #10, spot on.
 
It is a common problem, and it’s why Larry Brumfield included in his cylinder head installation instructions a procedure to stress test block threads before installing the head.
 
Engines used in racing have Helicoil inserts in all the threaded holes in the block. The Helicoils are stronger than just the threads in the cast iron because they are a slightly larger OD size and are spring steel.
Click to expand...


Nuclear qualified - if that is important to you. You just have to hire two quality control inspectors who are "process certified" to observe as you do it.


Joe K
 
Neil Mylar LakewoodCA said:
The cylinder head gasket that I am using is the best cylinder head gasket.

Can I reuse it or do I need to get another?

Thanks, Neil
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Which "Best" gasket did you use? The copper one or the Graph-Tite one"?

If you used the copper one, it can be re-used if undamaged, first, carefully remove any gasket sealer you may have put on, then it put it in an oven at 350° for an hour, remove and let it sit to cool to room temperature.

I don't know if it's possible to re-use the Graph-Tite one or not, others here may know.
 
I had the same thing happen on the B engine I put in my Cabriolet. The stud came out very easily since the threads were gone. The key is drilling and tapping straight on for the helicoil insert. If done properly the new stud will align well with the head. If it is crooked at all, the head won’t go on. Good luck!
 
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