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Discussion Starter #1
I have a question to those of you using the ARP head stud kit.

I currently have a set of the ARP head studs installed on my 3.1L engine. You may have heard me bitch lately about the hks metal head gasket not sealing. Since I have exhausted all other avenues of investigation as to my problem with the gasket sealing, I am wondering if the ARP studs might in fact be my problem.

My question:
When you installed the studs, did the shank sit flush with the block, or were there threads still showing.

On mine, I have threads still showing (about 2.5 threads above the block surface). This is different than any other stud I have dealt with. On all other studs I have used, the shank would sit flush with the surface in which the hole was drilled.

I did retap and clean all of the bolt holes, so I am sure that the set of studs I have are sitting properly as they were cut. I am just not sure if they were cut properly by ARP.

My current theory about why I cant get my HGs to seal is that the studs may be distorting the block surface under torque.

Thanks in advance for your insight,
Wayne
 

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Good call, Wayne!

You are right to consider this.

Most of the stress and strain on a female thread part are at the first threads. Assuming elastic (no stretching past yield) the stress drops linearly to zero at the threads at the tip of the bolt/stud.

I'll compare an OEM head bolt with a loose head when I get home and let you know if all threads protrude and by how much. With metal gasket, though, the deformation you are considering is a much greater problem.

Later,
Al
 

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Re: Good call, Wayne!

I have all the setup you mentioned earlier, head ,studs and gasket. When the block is prepped you should have a good chamfer on the threaded holes for the studs/head bolts. All threaded holes that are making a contact surface seal, I.e. head, oil pump pickup tube in the block, valve cover gasket to mention a few. when a bolt/stud is tightened into the threads the tendancy is to push up the metal around the threaded hole when torquing the part down, so with the chamfer done all the metal push does not affect the sealing surface.
When I installed my studs, I used two of the nuts and twisted the stud into the hole until it was tight in the hole. I think there was one thread above the sealing surface of the block.
I dont know why you are having so much problems with this thing, but I would suggest you make sure it is the correct gasket for the bore size, and that it locates correctly on the deck with the locating dowels.
 

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Loosetoe

this has been addressed before. First off, you do not want to double nut the stud and drive it into the hole. This creates additional stess on the threads. It should be placed into the block hand tight until it will not longer tighten. You can place oil on the threads before inserting. As far as threads showing, you may or may not have threads showing even after you chase the hole with a tap. Most of mine went all the way down, but some did not. To resolve this problem you will have to purchase a special bottom tap that will get the last bit of threads cleaned up at the bottom. This tap should be used after you run the initial tappered tap into the hole. Also, you want to get the grade of tap that is for chasing holes and not cutting holes. However, I don't think it will affect your setup. Also, the torque setting is critical. I would not use the ARP moly lube unless you have a 1 torque gasket. I would just use oil and torque it to 65ft-lbs(oil only) or the lower 52ft-lbs(moly lube). I hope this helps as ARP cannot even provide correct technical support for their products they sell(they do not make them).
 

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Re: Loosetoe

Ok James, let me clarify. I did mean to imply the studs should be tightened as if you were tighting a nut, but bottom the stud in the hole. Also I did not find any torque specs on my boxes either when I went to torque the head, I went with the upper end of the torque spec. if bottoming the stud threads in the hole is that important, then machine the end of the stud off, rather then messing with the block. There is no way to tell how much material Nissan left at the bottom of the hole. These engines have somewhat of a problem with the studs on the left side of the engine getting cooroded in the first place so it is best to leave the threaded hole alone except to chase the threads. Oil is a good lub to use when you install the nuts on the studs, also when you install the washer, make sure the rounded side (outer edge of the washer) is on the nut side and not the head side. I had some problems one one stud with the washer turning on the head and not the nut. The washers are punched out so one side will have a sharp edge, that edge will aid in the torque procedure to keep it from turning on the head side of the washer when you torque the nut down. use a good torque wrench, and I suggest going 5 Lb torque increments and not the three torque increments the book says to do.
 

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Great forum!

Goes to show, tightening a head bolt is no trivial issue.

Heard that Felpro made some V-8 head gaskets with washer inserts so that torqueing would tighten up metal-to-metal contact on the washers. Thus, the squish (compression) on the compressible part of the gasket was controlled. Also, this would minimize distortion and cracking potential of the head.

The Nismo metal O-ring type performance head gaskets look pretty trick, but probably pretty expensive what with machining the block and all. Anybody try these?

Later !
-------- Al
 

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BTW... re head bolt washers...

One Nissan OEM part I'm not happy with is the head bolt washers. Using the turbo head bolt and new washers I had galling on all washers. Gonna try and find me some properly hardened alloy washers for the next time.

----------- Al
 
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