Vanagon head stud installation procedure?

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schopp
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Vanagon head stud installation procedure?

Post by schopp » Fri Nov 26, 2021 3:49 pm

Greetings,

I am in the process of a complete rebuild of my 82 Vanagon motor. I have everything completely disassembled and cleaned. I am using the Camper Special kit offered by the type 4 store. This is a very comprehensive kit which was part of the appeal.
Part of the kit is new ARP head studs. By design of the type 4 some of the studs go into blind holes and some go into through holes. Currently none of the holes will accept a new stud easily. Certainly not by hand. It seems as if the threads need cleaning up a bit. Full disclosure, the old studs were challenging to remove, but they all came out in the end with some heat needed on a couple of them.

Due to the "tightness" of the threads, I ran a tap (M12-1.5) through one of the through hole locations. I was surprised at how much material was getting "cleaned" out. Now the new stud threads right in by hand very easily. Too easily is my concern. If I thread it all the down, the stud still has the ability to rock a bit back and forth, not significant, but appreciable... more concern creeping in...

Should I continue to chase the remaining threads?

Am I going to run into trouble later with the through hole studs being too loose when I go to torque my cylinder heads?

How do I set the height of the through hole studs? Meaning, what is the right height? Should I bottom out the studs in the blind holes?

This is my first time with an aircooled torn down, so I am learning for sure.

Thanks for any help and guidance you can provide.

-Jason

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Amskeptic
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Re: Vanagon head stud installation procedure?

Post by Amskeptic » Sat Nov 27, 2021 2:49 pm

schopp wrote:
Fri Nov 26, 2021 3:49 pm
Greetings,

I ran a tap (M12-1.5) through one of the through hole locations. I was surprised at how much material was getting "cleaned" out. Now the new stud threads right in by hand very easily. Too easily is my concern.
Should I continue to chase the remaining threads?

How do I set the height of the through hole studs?
-Jason
Find an open hole and run a stud down to flush in the inner case. Consider that your depth gauge. Make the blind hole stud the same length as the open hole stud so long as it is on the same level (upper or lower)

You do not want loose studs, they have to hold back engine oil on the open holes. I would only tap enough to get started, and maybe try an 11-1.5 to finish the hole only enough to reduce your installation turning torque.

With that loose stud you mentioned, I have to ask if your dimensions are all correct. Try a cleaned die original stud in that hole. Is it tighter? Does an original stud go in easier or as tight as the ARPs? You can use red stud and bearing LocTite to hold things in place during assembly. Studs will usually "set" themselves over the next several thousand miles.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

schopp
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Re: Vanagon head stud installation procedure?

Post by schopp » Mon Nov 29, 2021 4:57 pm

Colin,

Thanks for the thorough response. I have referenced this site for quite some time now as a long time aircooled owner and I really appreciate the time that you and others spend teaching those of us in need of answers...and moral support at times.

Prior to running the tap through, I used a thread gauge to triple check the thread pitch and I used a set of calipers to check the diameter of my tap to the diameter of the new stud. At the time, I was paranoid of doing the wrong thing. I also at the time (prior to using the M12 tap) and in hyper state of alertness (paranoia) I had run an M11-1.5 tap down the holes just for kicks to clean them up gently.

The old studs and the new studs exibit similar looseness on the freshly tapped hole. Arguably the new studs are a bit tighter to thread in. On the holes that I didn't run the tap through, the old studs are squeaky tight, but the new studs won't thread in easily. In fact, I had to double nut them to get one to thread in and with a bit of force too. Most all of the holes act this way. The ones I tried anyway.

At risk of sounding like a complete wacko, here is one hypothesis for what has occured-

The new studs are bit on the high side of acceptable tolerance. When I noticed that the new studs were tight, I assumed I needed to chase the threads with a new tap from my set. (now the crazy part)-this new tap is also on the even higher side of acceptable tolerance. In the end, I created an over sized hole, for my oversized stud. That all sounds to far out there though....

On a good note, I work at a machine build automation shop. Tomorrow I am going to bring my old stud, my new stud, my tap and my case half and I am going to explain what has occured to one of the old machinist and see what he says.

Back to the questions -
Should I use red loctite on all of the studs, or just the one that I may have screwed up? Is there any way to be sure if the hole is TOO BIG? There are lots of threads that get engagement on those studs, so I would think you can get away with a little error, but this is all new to me.

Thanks again

Jason

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Amskeptic
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Re: Vanagon head stud installation procedure?

Post by Amskeptic » Tue Nov 30, 2021 3:35 pm

schopp wrote:
Mon Nov 29, 2021 4:57 pm
Colin,

Thanks for the thorough response. I have referenced this site for quite some time now as a long time aircooled owner and I really appreciate the time that you and others spend teaching those of us in need of answers...and moral support at times.

Prior to running the tap through, I used a thread gauge to triple check the thread pitch and I used a set of calipers to check the diameter of my tap to the diameter of the new stud. At the time, I was paranoid of doing the wrong thing. I also at the time (prior to using the M12 tap) and in hyper state of alertness (paranoia) I had run an M11-1.5 tap down the holes just for kicks to clean them up gently.

The old studs and the new studs exibit similar looseness on the freshly tapped hole. Arguably the new studs are a bit tighter to thread in. On the holes that I didn't run the tap through, the old studs are squeaky tight, but the new studs won't thread in easily. In fact, I had to double nut them to get one to thread in and with a bit of force too. Most all of the holes act this way. The ones I tried anyway.

At risk of sounding like a complete wacko, here is one hypothesis for what has occured-

The new studs are bit on the high side of acceptable tolerance. When I noticed that the new studs were tight, I assumed I needed to chase the threads with a new tap from my set. (now the crazy part)-this new tap is also on the even higher side of acceptable tolerance. In the end, I created an over sized hole, for my oversized stud. That all sounds to far out there though....

On a good note, I work at a machine build automation shop. Tomorrow I am going to bring my old stud, my new stud, my tap and my case half and I am going to explain what has occured to one of the old machinist and see what he says.

Back to the questions -
Should I use red loctite on all of the studs, or just the one that I may have screwed up? Is there any way to be sure if the hole is TOO BIG? There are lots of threads that get engagement on those studs, so I would think you can get away with a little error, but this is all new to me.

Thanks again

Jason
I am handing you off to your machinist. So much can be explained in person. You may need to have an insert installed if the hole is too big.

I have always double-nut installed studs with a little Permatex Aviation to serve as a lubricant/sealant all at once.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

schopp
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Re: Vanagon head stud installation procedure?

Post by schopp » Thu May 26, 2022 4:32 am

I realized that I never followed up on the machinist's info that he shared with me.

Taps have an oversize value. In metric this is notated as D"X", where "X" is the over sized value from the dimension of the thread. A D1 tap would be a tiny bit bigger than exact dimensions, D2 would be a bit bigger than that and so on. A typical general usage D value would be a 4 or a 5. In my instance, my "Gear wrench" brand tap set didn't include this additional classification. Mr. Machinist sent me home with a D4. I ran that through all threads.

Interestingly, some holes were barely "cutting" anything and other holes were removing an appreciably amount of material. In the end I had some studs (half?) that felt a little loose. On those studs, I took a ball peen hammer and peened the far end of the threads so when the stud was almost all the way threaded in the peened threads would interfere slightly with the threads in the case and in turn tighten up at the last couple threads (turns). MSC's website has a nice write-up on this info.

Embarrassingly, I just now got the motor assembled in the last week or so and all seems well, but I'm no where near broke in yet with less than 100 miles on it, but only after the requisite 20 minute 2500 RPM break-in cycle of course. That was a nerve racking endeavor, but a right of passage I suppose.

Anyways, thanks for the continued support. If anyone has questions on the LN Engineering camper special kit or the CB Performance Gen4 EFI kit, that's what I went with. Still learning the EFI, but so far so good. Still getting my feet wet for sure.

Jason

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