Bad Stud thread

[DBSHELTON]

Trying to finish my spare engine and was torquing the head nuts. Everything went fine at 25ft lbs, 36 ft lbs, 48 ft lbs, and then finishing up at 55 ft lbs and the threads failed on #14 on the chart!!! Damn, now I gotta pull the head and helicoil that hole. Worst part is wasting the new head gasket!

[Flathead]

At least it's a hole you can dig yourself out of!

[1crosscut]

Yeah that is a bummer.
If you're drilling free hand for the helicoil make sure you have an extra set of eyes watching 90 degrees from where you are so as to make sure it's drilled straight up and down.

[Jack Shaft]

Better yet rent a mag drill from the local rental. Set it down on the deck,line it up,turn the magnet on and drill square every time.Consider a timesert instead of a helicoil, its a better product.

[DBSHELTON]

I am going to use the head for a drill guide since the drill bit for the helicoil will fit through.
Before I pull the head, should I over-torque the nuts to maybe 75ft-lbs to make sure all the threads are good and this won't happen again?

[Licensed to kill]

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I broke a stud off when changing them out. I drilled out the hole and tapped to the next size (1/2" IIRC) then made a stepped stud which I later found out that you can buy. Doesn't matter, i would have made mine anyway. I used my mag drill as jack suggested to drill and tap the hole to ensure that it was straight. Using the head as a guide would work as well. No real need to monkey around with help coils or inserts. You have to drill and tap it anyways, just put in a oversized base stud.

[Greg Jones]

No don't over torque to 75 foot pounds. Absolutely not!

[sofield]

Bratton's supplies a tool jig kit #8235 that allows you to drill out the stud without disturbing or removing any of the other studs. The jig comes with a locating guide and bushings, a burr to center the hole, drill bit and two taps including a guide bushing to install a Helicoil. The DRILL BIT STINKS, BUY A CARBIDE ONE. I just completed doing 3 studs in a little over an hour. With your stub breaking at such a low torque setting you might consider replacing all of the other studs.
Take the job slow and easy
Good luck

[mike657894]

I broke a stud before. I used the head as a guide with the drill bits wrapped in electrical tape to bush them to the hole. you can also use tape to make a mark of depth on your drill bit. I went without a depth mark and drilled through my block to the water jacket, and have to thread seal that stud now. dont make that mistake.

[DBSHELTON]

I went ahead and drilled the threads out through the head for the helicoil. Very easy since the hole in the head was the correct size for the 29/64" bit.

In my poor boy days I would drill the head out to 17/32" for the tap to fit through and install the Helicoil through the head. LOL!

[katy]

If you didn't put any sealer or paint on the head gasket it can be re-used.
Put it in the oven or bar-b-que for 15-20 minutes and then let it air cool before re-installing it.

[john charlton]

I bought a rebuilt (so they said ) engine very cheap . It was cheap because someone had put a helicoil in but not straight . I screwed a new stud in and it looked like the leaning tower of Pisa . HHMMM I thought what to do, what to do . The helicoil was large meaning I did not think I could go the next size up if there was one . So a master plan sprung into action I screwed a new stud hard home in the helicoil and took a template of the lean and marked the stud with a sharpie . Put the stud in the vise with two UNC nuts on the bottom and with a suitable tube cold bent the stud to match the template . Replaced the stud put the head on and torqued to 65 ft/lbs and let it set for a while all looked good .I think this is a permanent cure I cant see this large helicoil pulling out of the block and the bent stud has not lost vertical strength . I checked the motor out new pistons etc etc so was rebuilt I bet the guy in the shop got it in the neck afterwards . In service it will be torqued to 55 ft/lbs

John in cold dark Suffolk County England .

[DBSHELTON]

Originally Posted by katy

If you didn't put any sealer or paint on the head gasket it can be re-used.
Put it in the oven or bar-b-que for 15-20 minutes and then let it air cool before re-installing it.

Even a Graphite composite gasket?

[Ernie Vitucci]

Good Job, John...I would not have thought of that...Ernie in Arizona

[Y-Blockhead]

Bratton's has head studs with an oversize thread (½-13) on one end if you ever find you need it. I would think that would be better than a heli-coil.

[DBSHELTON]

I figured since I had another gasket I would go ahead and use it. Looks like I was successful on my 2nd time.

[BRENT in 10-uh-C]

Originally Posted by DBSHELTON

I figured since I had another gasket I would go ahead and use it. Looks like I was successful on my 2nd time.

Exactly what is the reason why you cannot reuse the first head gasket?

Unless you unnecessarily coated it with some type of sealer that caused it to tear when removed, then reuse it. If you are worried, then anneal it and it will be ready to reuse.

[DBSHELTON]

If I didn't have another one I would have given it a couple of coats of copper spray and re-used it. Heck, I have even used aluminum spray paint successfully. I did keep it just in case.

[Y-Blockhead]

Originally Posted by BRENT in 10-uh-C

Exactly what is the reason why you cannot reuse the first head gasket?

Unless you unnecessarily coated it with some type of sealer that caused it to tear when removed, then reuse it. If you are worried, then anneal it and it will be ready to reuse.

Didn't he mention he had a Graphtite head gasket?

[Pete]

Originally Posted by DBSHELTON

I am going to use the head for a drill guide since the drill bit for the helicoil will fit through.
Before I pull the head, should I over-torque the nuts to maybe 75ft-lbs to make sure all the threads are good and this won't happen again?

Just for your information, 75 is a very conservative number for testing deck threads on a flathead Ford. We test at 100 ft lb.

Testing should be done while doing machine work on the block and before any cleaning. This way you are assured there will be no drilling or machining after assembly with the consequent chips getting inside.

Threads should be chased with a tap, not a chaser. You CAN NOT get an accurate torque reading with rust and scale left in the threads.

[DBSHELTON]

Thanks for that bit of info.

[john charlton]

Correction 2 UNC nuts on the bottom of the stud not UNF OOOOOPS !!!

John in same place same weather .

[BRENT in 10-uh-C]

Originally Posted by Y-Blockhead

Didn't he mention he had a Graphtite head gasket?

The way I took it (-when Katy suggested annealing) was "Can this also be done on a graphite gasket?" -as in can this be done on this type gasket also.

I will tell you straight-up that the Model-A deck surface will NOT hold 75 lbs of torque without distorting. If the deck is distorted or the RA finish is not good enough, you will never get a Graphite gasket to seal (-new or used!!).

Originally Posted by Pete

Just for your information, 75 is a very conservative number for testing deck threads on a flathead Ford. We test at 100 ft lb.

Testing should be done while doing machine work on the block and before any cleaning. This way you are assured there will be no drilling or machining after assembly with the consequent chips getting inside.

Threads should be chased with a tap, not a chaser. You CAN NOT get an accurate torque reading with rust and scale left in the threads.

Pete, since the Model-A block uses studs that are stationary, are you/we referring to rust inside the threads of the block affecting torque values??

[Pete]

Originally Posted by BRENT in 10-uh-C

The way I took it (-when Katy suggested annealing) was "Can this also be done on a graphite gasket?" -as in can this be done on this type gasket also.

I will tell you straight-up that the Model-A deck surface will NOT hold 75 lbs of torque without distorting.

>Tell that to several circle track guys and the guy that was top fuel 4 banger
eliminator at the Antique Nationals a couple of times.


Pete, since the Model-A block uses studs that are stationary, are you/we referring to rust inside the threads of the block affecting torque values??

Yes.

[DBSHELTON]

Here it is in it's current state. I will take a plastic razor blade and trim the blue sealant off after it sets up around the water neck. It just looks better.

[Ed in Maine]

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When working on the Model A engine there is no other worse feeling than going for 55 ft-lbs and feeling the torque wrench start to "cave in on you"! I recently purchased a Model A and about a month after I had it, the crankcase got a lot of water in it. I had a heck of a time getting the head off of the engine and found that who whoever rebuilt it, had two improperly drilled Helicoils which resulted in two leaning studs. I like John Charlton's idea of bending a stud but John wasn't at my house when I needed him! I felt that the engine had been together so it had to go back together the way was. I put all the good studs into the block. I put on the head gasket and the cylinder head on the block. Then using NeverSeize, I installed the two troublesome studs using a single nut threaded on half way and a spare stud threaded into the other half of the nut to stop any turning. When the studs hit the top of the hole in the block, the treads are lined up enough to start OK, it is only as the stud gets deeper that there is more and more interference with the stud and the upper area of the cylinder head. This is where the NeverSeize comes into play, all of the stud was coated and I was surprised that with the wrench on the nut and the spare stud on top of the nut, locking the assembly together, I could turn the stud down into the Helicoil to the required depth. I know this isn't the best but who wants to pull the engine and take it to a machine shop for correction. I worked for me and everything torqued down just fine to 55 ft-lbs. After 1000 miles there is no water leakage. Ed

[rocket1]

In the bargain rebuilt engine I purchased when I screwed the head bolt into a helio coiled hole the stud was leaning so I marked the side and bent it in the press so it would be vertical.The only problem now is that the head would have to come off to remove the stud.So I remember which one it was I put a dab of nail polish on it,my secret!