Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Exhaust Locking Tabs

Does anyone know where to source these? Using Phil's engine removal video and these seem to have a very limited life.

One of the first things I replaced on my car was the exhaust studs (with ARP high strength stainless studs) and reduced hex flange type all metal locking nuts (aka jet nuts) which allows much easier socket access. And no more loose exhaust nuts. Those locking tabs seem ill suited to a high vibration exhaust application.

I also replaced the cylinder head ends of the exhaust pipes to allow using a modern Harley style better exhaust sealing ring, but that's another story, which I think I documented on this forum years ago.

Thank you! Would you be willing to PM me the details of where you got the exact exhaust studs & jet nuts that fit our X121s? I am a bit of a novice at this part of being a mechanic. I am however 85% done with my Engine pulling manual using MorganCustom & Phil Bleazey instructions.

I THINK this might be what Bleazey mentions:
S&S Exhaust Bolts like Phils

"BZ Note: I have replaced the flange studs and nuts with 5/16 18tpi UNC x 1 1/4 long socket cap screws in stainless steel. They make a neater job as there is not really enough clearance for the socket spanner to undo the original hex nuts. Drill and wire the SS nuts - no need for fancy tab washers then."

I do not use socket head screws such as shown in your link for exhaust systems. I'm not a fan of using that type of fastener in an alloy cylinder head as I believe it increases the risk of stripping the threads in the head due to the wear and tear of install/removal each time the exhaust is removed. I might feel differently if I could reach the screws with a torque wrench. If the heads have had thread inserts installed then I would say those screws are fine.

I prefer to use studs, similar to the factory setup, but in a high strength stainless steel. ARP makes racing quality fasteners for a variety of applications.

Some links:

For some light reading, check out the ARP catalog https://arpcatalog.com/94/
Better to buy their products from a retailer, as ARP itself really isn't well set up for small orders.

And for purchasing the studs and nuts, check out Pegasus Auto Racing Supplies: https://www.pegasusautoracing.com/productdetails.asp?RecID=23074
And: https://www.pegasusautoracing.com/productselection.asp?Product=MS21042

You can also find ARP products on Amazon and other online retailers.

Edit: Forgot about Totally Stainless!, They are a great source for all kinds of stainless fasteners: (click on their .pdf catalog to get an overview of their offering. They also have paper catalogs.
https://shop.totallystainless.com Online presence is dated, though.

I'm not certain about the stud length, but can check later tomorrow to see what I actually used.

Loads of info in this THREAD.

Exhaust studs

A reaction on TM #846463

I have recently worked on my exhaust too, I am just writing an article for TM about the flexible rubbers under the Muffler.

I could never get the right studs on the internet.
The studs delivered by for instance the X-Wedge expert ‘Zodiac’ as exhaust studs are not the original and even the wrong ones.

I know one shop who may sell quality 8.8 steel but they are not on the internet.

So I worked with S.S. 5/16 x 18 bolts.

I agree that Stainless steel is not good with an aluminum Cyinder-head.
And Steel Stainless is absolutely not as strong as 8.8 steel, but . . .

With all our experience with big aluminum sailing-boat masts I use for everything on the M3W Tefgel.
Tefgel can easily be used with heat of more that the 220 degr. C which the cylinder head gets maximum in general.
And Tefgel nearly perfectly protects for electrolyze problem between the stainless steel bolts or refits I used on our Aluminum masts. They last for years without damaging the aluminum structure.

After some tries I found that the Allan types - 2,5 inch long thread - fitted the best because my round-wrench for 5/16 ( or 13mm ) fits over the Alan bolt head.
So I can tight a separate 5/16 nut.
With a hexa nut bolt you are in trouble.

It is better to use the bolt as a fully fitted stud and use a separate hexa nut to make the fix.
I have used the bolts you described too and they got loose and damaged the aluminum thread.
You absolutely do need the whole length of the thread inside the head.

It is wise to recut the thread inside the head very carefully with a 5/6 cutting iron.

Bring some - even more than some - Tefgel on the thread of the Allan bolt.
With the nut totally brought to the Allan-bolt head.
You turn the 2,5 inch x 5/16 Allan bolt carefully and fully in the cylinder head.
When tight you use the appropriate round wrench on the hexa nut and tight it hand tight.

Scheck ones in a while.

This will do it for years till you – and me - can find the same bolt in a 8.8 quality

Reminds me of the IT definition of "recursion"...
Recursion = see Recursion

[Andy - think you meant to put in a different link]

If I ever (when?) have to fit my spare engine I'll be fitting thread locking Helicoils before it gets near the chassis so that the female thread strength will not be an issue and the studs will stay in place.

I use these too - easy to fit and do the job.

For the exhaust system, I use high-temperature mounting hardware intended for air-cooled Porsche exhausts and turbos; the nuts are marked "GA" and the bolts "GB." They never need retightening because they expand along with the parts they secure and return to their original dimensions upon cooling. The stock studs are of good quality—5/8 UNF and 5/8 UNC—though they could be 5 mm longer, as there is sufficient space in the cylinder head. In the ARP catalog, however, I only found exhaust studs designed for cast-iron cylinder heads, which have a shorter UNC threaded section.
Water-cooled engines present fewer issues regarding the attachment of the exhaust manifold to the cylinder head and can be assembled using standard automotive-grade fasteners; however, the turbocharger itself requires higher-quality hardware—you cannot mount a turbo to an exhaust manifold using A2/A4 stainless steel or standard 8.8 through 14.9 grade bolts without eventually having to retighten them to the point of bolt failure.
To repair damaged cylinder head threads after installing a metric Heli-Coil, I use 8mm diameter Porsche 3.2L studs with a 1.25mm pitch. If the cylinder head threads are in good condition, I take a long 8mm bolt (1.25mm pitch) and use a lathe to cut UNC threads onto its smooth shank; furthermore, GA/GB grade hardware contains nickel and offers excellent corrosion resistance at high temperatures (austenitic steels) PDF.