engine and drivetrain EXhaust manifold stud fitment - cause for concern?

[Healey3000]

Hi,

 

The replacement studs I purchased from IE don't have the unthreaded section that the ones I removed have.  This means they won't stop against the head on the face but will go all the way in before running out of thread.

 

I installed the upper row with Loctite 242, as recommended and don't like the feel as I tighten them down.  They don't want to come to a positive stop and I'm worried about torqueing them too much for fear of cracking something in the head casting.  This also means that once I install and tighten the nuts, there is a very high probability that the studs will turn, breaking the seal.  The stud on #4 is clearly sitting deeper than the rest already.  Will a full cure after 24 hours be a strong enough bond to prevent stud rotation?

 

Thanks.

[Buckeye]

No it will not. ask me how I know. I installed full threaded stud on exhaust flange and after fastened down pipe with nut, stud advanced on me and broke the flange. Suggest you install appropriate studs. 

[stone02]

CAUTION; when you install studs in the upper holes of the

exhaust side of the head you can VERY easily run the stud

in TOO far and be against the VALVE SPRINGS!!!!!!

if you use a thread locker fluid you must degrease to hole

first and then install the stud. use CRC brake parts cleaner.

the lower holes are blind so this is not a problem. the shoulder

type studs are hard to find. contact an engine builder or

someone parting out and old head and get good used ones.

stone

[Simeon]

Bit confused but from what I remember about stud theory (and this may not be the same for metric studs) is that the thread form on the section that is run into the head is slightly different so that it is a tight fit in the hole. Plus if it is run down until the non threaded section interferes and stops it this prevents the loads being properly transferred down the whole length of the thread. 

 

An all thread rod wouldn't do the same thing plus the risk of fouling the valve gear. 

[Healey3000]

1 hour ago, Simeon said:

Bit confused but from what I remember about stud theory (and this may not be the same for metric studs) is that the thread form on the section that is run into the head is slightly different so that it is a tight fit in the hole. Plus if it is run down until the non threaded section interferes and stops it this prevents the loads being properly transferred down the whole length of the thread. 

 

An all thread rod wouldn't do the same thing plus the risk of fouling the valve gear. 

Hi,

 

You are correct about some studs having a dual taper.  These, however, are simple, straight ones.  It looks like IE simply re-badged metric setscrews as "studs".  It's surprising that they would sell a product that is capable of running into the valve springs or cracking flanges.

[Healey3000]

Thanks for the caution, folks.

 

Fortunately, I have the originals so I'll clean them off and use them instead.  This does raise a doubt in my mind about the recommended procedure for installation.  Would it not be better to apply Loctite to the thread and install it along with the manifold and nut right away?  That way, the Loctite is allowed to sit for 24 hours to cure in its torqued condition and is not disturbed again by the installation of nuts.  If the lower row is installed first, they will act as guides for the gasket and manifold.

 

This seems more logical than curing just the studs.  What say?

[Simeon]

Check the Loctite website for the correct application. It may say that parts *shouldn't* be loaded for 24 hours. I would interpret that as set the studs, leave them and then add nuts.

 

Reality is, I don't think that they are that critical in the grand scheme of things so either technique will work. It's not a bolted flange in a nuclear power plant. 

 

 

[Healey3000]

The nuts won't come off the original studs so my plan to reuse them may be in jeopardy.  A few places seem to show the correct style of studs, at least in the photographs.  I went with the IE ones so that I could tighten them more easily.  Oh well, car won't be on the road this weekend...

Edited September 3, 2016 by Healey3000

[ray_]

10 hours ago, Healey3000 said:

The nuts won't come off the original studs so my plan to reuse them may be in jeopardy.  A few places seem to show the correct style of studs, at least in the photographs.  I went with the IE ones so that I could tighten them more easily.  Oh well, car won't be on the road this weekend...

 

 

You may already be aware, but those nuts are supposed to be copper, to mitigate seizing,

 

Good luck,

[Healey3000]

1 minute ago, ray_ said:

 

 

You may already be aware, but those nuts are supposed to be copper, to mitigate seizing,

 

Good luck,

Yes, they should be.  I have new Cu ones but the originals I'm battling with are a well-rusted set of steel locknuts.  Curiously, they are installed with the locking portion facing the manifold.  I thought they were to be the other way around.

[Healey3000]

The plot thickens.

 

I went over to 002 Salvage to buy new studs.  He brought out a set of fully threaded ones, just like the IE studs, but without the hex key.   According to 002, the factory studs are fully threaded and the aftermarket studs have the shoulder.

 

They had the shoulder style studs too, so I bought a set. I am now confused about the whole thing.

[jimk]

3 hours ago, ray_ said:

copper

They are copper plated.  Take a magnet and see. Copper nuts won't hold much, too soft.  The copper plating does the same as anti seize with copper in it.

Edited September 3, 2016 by jimk

[ray_]

9 minutes ago, jimk said:

They are copper plated.  Take a magnet and see. Copper nuts won't hold much, too soft.  The copper plating does the same as anti seize with copper in it.

 

I think you're right.

 

Again.

 

[Healey3000]

14 minutes ago, jimk said:

They are copper plated.  Take a magnet and see. Copper nuts won't hold much, too soft.  The copper plating does the same as anti seize with copper in it.

Now that makes sense!