Copper flanged exhaust nuts, DO NOT USE THEM Options

[iankarr]

Just curious…is there a mechanical issue with the studs coming out with the nuts? That happened on my car and I just put them back in like “bolts”.

I also used loctite 510 Hi temp sealant around the exhaust mating surfaces and it worked amazingly well…

[VaccaRabite]

Just curious…is there a mechanical issue with the studs coming out with the nuts? That happened on my car and I just put them back in like “bolts”.

I also used loctite 510 Hi temp sealant around the exhaust mating surfaces and it worked amazingly well…

The threads in the head are soft aluminum. They can strip out. You want to be able to leave the studs in place to preserve the head threads. When the heads strip out its a pain to fix them.

Zach

[rhodyguy]

A MAJOR pain! Then you go shopping for step up studs, the drill bit and correct sized tap (that you may never need again). Heaven forbid you go too deep with the bit. The problem is the oval hole nut locking feature and potential seized up threads. MOM and the proper nuts. Name BRANDED nuts can cost a small fortune.

[ClayPerrine]

Years ago I had to have a head welded up the night before the MUSR so we could make the event. The car was running great, but on the way home from work, it spit an exhaust stud. The hole had been drilled and a step stud installed. This left the wall between the stud hole and the combustion chamber too thin. So it blew a hole from the combustion chamber to the hole for the stud.

I got home and immediately dropped the engine and pulled the head. I was pissed and in fix it mode. I took a still warm cylinder head to the local VW machinist (Lyle Cherry.. RIP) and he welded it up and re-machined it that evening. I took it back to the house and reassembled it. The next day we drove it to the event, and didn't have a single problem with the car the whole weekend.


I don't really like stepped studs or helicoil/timecert fixes. I feel there isn't enough meat on the heads to put them in safely.

These days, a set of new heads is the way to go. The current ones are 50+ years old and very questionable about what has been done to them over the years.

[VaccaRabite]

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The nuts in question are commonly available and sold as exhaust nuts. I got mine from Auto Atlanta - but many places sell them. The have a copper color to them and the bore is slightly oval. The are designed to lock on to the stud - which I did not know at the time. They go on tight and you can not remove them without pulling the stud. Modified the first post of this thread. There are obviously some flanged nuts that work well. The ones I got that had the ovaled bore did NOT work out for me.

Zach

[MartyYeoman]

It's also important to watch that there's sufficient clearance below the ear at the head. With no clearance the load path wont produce crush on the copper sealing ring no matter how much torque you apply to these nuts.

[Root_Werks]

Did you use anti-seize?

Doesn’t matter, they are a crush fit, for a stock vehicle don’t use them.

(IMG:style_emoticons/default/agree.gif)

Yup, those will turn out studs 100% of the time.

You're on it Zach, just regular nuts with washers works just fine.

[Jim C]

Wish I had know this last weekend.

[r_towle]

In a DM I said, and I would love to see, stub pipes.
So, modified and shortened SSI heat exchangers bolted to stub pipes.
This way we can get a firm and frankly better connection to the head, and create a much simpler way to remove the HE for engine drops.

[rjames]

In a DM I said, and I would love to see, stub pipes.
So, modified and shortened SSI heat exchangers bolted to stub pipes.
This way we can get a firm and frankly better connection to the head, and create a much simpler way to remove the HE for engine drops.

That's a really good idea.

[IronHillRestorations]

All the copper coated flange nuts that I’ve seen are prevailing torque, or locking, nuts, which will often cause the exhaust studs to back out. I run a tap through them. Non locking flange nuts are available, but harder to find, and not copper coated.

[930cabman]

Years ago I had to have a head welded up the night before the MUSR so we could make the event. The car was running great, but on the way home from work, it spit an exhaust stud. The hole had been drilled and a step stud installed. This left the wall between the stud hole and the combustion chamber too thin. So it blew a hole from the combustion chamber to the hole for the stud.

I got home and immediately dropped the engine and pulled the head. I was pissed and in fix it mode. I took a still warm cylinder head to the local VW machinist (Lyle Cherry.. RIP) and he welded it up and re-machined it that evening. I took it back to the house and reassembled it. The next day we drove it to the event, and didn't have a single problem with the car the whole weekend.


I don't really like stepped studs or helicoil/timecert fixes. I feel there isn't enough meat on the heads to put them in safely.

These days, a set of new heads is the way to go. The current ones are 50+ years old and very questionable about what has been done to them over the years.

Is metal fatigue the question with 50+ years old aluminum?

[ClayPerrine]

Years ago I had to have a head welded up the night before the MUSR so we could make the event. The car was running great, but on the way home from work, it spit an exhaust stud. The hole had been drilled and a step stud installed. This left the wall between the stud hole and the combustion chamber too thin. So it blew a hole from the combustion chamber to the hole for the stud.

I got home and immediately dropped the engine and pulled the head. I was pissed and in fix it mode. I took a still warm cylinder head to the local VW machinist (Lyle Cherry.. RIP) and he welded it up and re-machined it that evening. I took it back to the house and reassembled it. The next day we drove it to the event, and didn't have a single problem with the car the whole weekend.


I don't really like stepped studs or helicoil/timecert fixes. I feel there isn't enough meat on the heads to put them in safely.

These days, a set of new heads is the way to go. The current ones are 50+ years old and very questionable about what has been done to them over the years.

Is metal fatigue the question with 50+ years old aluminum?

I don't know about metal fatigue, but repeated welding of the heads can result in aluminum porosity.

A rather long winded explanation on Aluminum Porosity

And with our beloved little cars either approaching 50 years old or past it, it is safe to assume that the heads have more than likely been reworked in the past. And in the 1980s, they didn't have the technology to weld aluminum like they do now. It is possible some DAPO took a gas torch and a long stick of aluminum and welded them up in the past. We have absolutely no way to know 40 years later.

With the cost of new heads being almost the same as it takes to repair an old one, I will be buying replacements in the future for all of my build needs.

[Literati914]

I think you will find 8 of these more to your liking.

Hey @Rhodyguy , check your PM's I need to get some of these from you, thanks.

.

[rhodyguy]

r not R.

[technicalninja]

That means there's two of you!

A pair of R/rhodyguys (IMG:style_emoticons/default/beerchug.gif)

Too funny (IMG:style_emoticons/default/av-943.gif)

Was someone else messing with you?

[rhodyguy]

Nope. Not that I’m aware of.