Full-bodied 7/16" repair stud

[jpian0923]

On the left is a Moyer 7/16" repair stud. On the right is a regular head stud.

The regular head stud is full-bodied 3/8", The shank stops the stud from going too far into the block.
The repair stud course threads are 7/16" but the shank is 3/8", there is nothing to stop the stud from being screwed in too far.
Also, there is nothing to torque against except JB weld and tension between the lower and upper threads. All the other studs you are torquing against the block.

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On the left is a full-bodied 7/16" grade 8 bolt (ignore the number of course threads, that's not my point) When you screw this in the shank stops at the block.
On the right is a Moyer 7/16" repair stud for comparison.


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When doing a lower thread repair with the head still on, using the 7/16" repair stud, you need to know how much stud to leave above the head so as not to screw it in too far. About 1 1/8" is what I used.


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If you are only used to screwing in head studs that stop at the block because of the shank, you might be confused and dumbfounded when screwing in a Moyer repair stud.
So, this is a wishlist and tech tip thread...I guess.

[romantic comedy]

Studs work like a rubber band. That is the way they hold things together. The steel stretches and exerts a force to keep the parts together.

You would not want to torque against the block. The studs should only be hand tight, but screwed in. Then when the parts are assembled, torque the nut to spec. The point of torque is to make sure that the bolt is stretched enough so that it exerts the required amount of force. (also a bolt needs to be a certain amount tight, so that it does not come loose)

Same with any bolt. You would not want the bolt to bottom in any hole.

[Al Schober]

You only need 1.5D to develop full strength of the threads. The original threads were 3/8, so needed 9/16 for full strength. The replacement studs have larger thread but don't need more strength and can live with less engagement. Brain fade - I'll let you do the numbers.
Use JB Weld to keep the water in the block.

[hanleyclifford]

I think I understand Al's concern here. If the threads in the block are clean, and the hole thru the head is reamed/clean, the possibility exists that torqueing down the stud will cause it to turn into the block too far such that not all the threads in the block will be engaged by the stud - possible, but not usual. The fix is to mark the head of the stud and count your turns into the block; then while torqueing make sure the stud does not spin. Sticky goo like Permatex #2 goes a long way towards preventing spinning. Also light machine oil on the fine threads and a quick chase of the nut with a tap can be helpful. Edit: Hanley corrected (again). After receiving an explanation from Don Moyer it seems that the threads on the 7/16" portion do not in fact go all the way thru that section and have a "stop" or are closed so that it is not possible to go too far into the block unless you torque like a gorrilla and break your way thru. Although I own one of the repair studs and always keep it on board I have never had to use it so I did not take note of this subtle but important feature until now. Sorry about my misleading and incomplete comments.

[hanleyclifford]

A Graphic Explanation

Here is what Don was talking about. In the first picture if you look carefully you can see that the 7/16" x 14 threads stop short of the end of the "fat" section. In the second picture the die has been turned onto the threads that go into the block as tight as I could manage by hand. See there is no way the stud could be turned any further into the block except by force that would likely damage the block as well. None of us would do such a thing.

[jpian0923]

Wish change; Instructions with repair stud.

I think I was somewhat of a gorilla. I wanted to make sure I was going to be able to torque to 35 Foot Pounds. My only experience with studs is the regular studs that stop. I expected the same from the repair stud. My fault. I change my wish...Instructions with the repair stud.
I can't be the only one that didn't know any better.

[hanleyclifford]

I think I was somewhat of a gorilla. I wanted to make sure I was going to be able to torque to 35 Foot Pounds. My only experience with studs is the regular studs that stop. I expected the same from the repair stud. My fault. I change my wish...Instructions with the repair stud.
I can't be the only one that didn't know any better.

There's at least two of us...

[jpian0923]

Hanley, thanks for saving face for me.

Ok, tonight I installed my 5th repair stud, in the last 3 months. The other 4 I used JB weld to seal the lower threads. Tonight I tried perm goo on the 5th...water seeped up through the stud. Not sure if, over time, the perm goo would seal, but I can't wait any longer, so I sealed using JB weld. Tomorrow I'll find out the results.

I'm sold on the repair stud, in fact, I now would like to change my wish list request again: Can all studs shanks have a smaller diameter than the thread diameter?! I'm a PITA, aren't I?

[hanleyclifford]

I'm surprised that Permatex #2 did not seal those threads. Are you running FWC (with a high pressure cap?) Do you know exactly where your water leak is? If you have a warped head or other surface problem all the new studs in the parts department won't fix it.

[jpian0923]

It might have sealed if I had waited longer. I only waited an hour because I was anxious. All the other non-repair studs I sealed with perm goo and they held the water back...but then again, I did give those much more time before testing.
I'm still RWC.

[67c&ccorv]

I think I was somewhat of a gorilla. I wanted to make sure I was going to be able to torque to 35 Foot Pounds. My only experience with studs is the regular studs that stop. I expected the same from the repair stud. My fault. I change my wish...Instructions with the repair stud.
I can't be the only one that didn't know any better.

Do you have a torque wrench?

[jpian0923]

Yes I do. Each tic on the scale is 5 foot pounds. I didn't actually know that until about 3 weeks ago. But that wasn't my real problem.

The problem was not knowing to not seat the stud into the block up to the shank.
What I've learned is to seat it into the block up to the shank and back it off a full rotation, or more.
Then when the head is on and you're torquing the nut, you'll have some room for the stud to spin inward into the block without torquing against the block.
Torquing against the block with the stud shank is likely what ruined the threads in my block.
The "rubber band" analogy is what helped me learn this...and installing 5 7/16'' moyer repair studs.

So, it's lower block threads torquing against upper stud threads that gives you the 35 ft lbs of torque, not lower stud shank (against block) versus upper stud threads.

This is my interpretation and at this moment, it's working.

I took her out for sea trials tonight and got her up to 8.2 mph (7.1 knots)

[YOUTUBE]nqiLRzqGIWE[/YOUTUBE]

I may have stuck my foot in my mouth again (and I'm wrong), but it won't be the last time!

[hanleyclifford]

At the risk of beating this thing to death I must disagree with your supposition that 35 lbs of torque can be transmitted to the lower threads going into the block. By the time you have built torque to that value most of it is being applied linearally head to block and the threads in the block can handle that nicely. The 35 lbs does not descend rotationally to the threads. To keep that at a minimum you should always chase the threads on old studs and nuts with tap and die, 3/8"x24 NF. It is a good idea to oil lightly both stud and nut. It is just fine to turn the studs into the block as tight as you can by hand.

[67c&ccorv]

I like using Loctite Red (permanent...but it will release with heat) for anchoring studs in blocks - heads - etc.

[romantic comedy]

There are many discussions to be had about torque, tension and load on connections.

This is an interesting video to get started.

http://www.youtube.com/watch?v=O96AUlIBkU8