Stainless manifold studs and nuts a good idea?

Joel K

Supporter
Looking for some guidance on this.

I plan on buying studs and nuts to attach the LS7 style flanges with down pipes to the stock Exhaust manifolds. Wondering if using stainless hardware would make it easier to remove in the future.
Are there any reasons not to use them? The stud size is M10.

Thanks
 

Ken Roberts

Supporter
I have a bunch of the original stock style LS7 studs. You are most welcome to have them Joel. They are stainless.

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Scott

Lifetime Supporter
I'm using stainless studs and copper nuts which are a one-time use item. If I wasn't using copper, I would use stainless steel. The other question is what, if anything, you're going to put on the threads.
 

Ken Roberts

Supporter
A good high temperature rated anti-seize

I just noticed that the stock nuts are magnetic.

I’ll see what the OEM service manual calls for regarding the threads.
 
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Ken Roberts

Supporter
The 6 bolts holding exhaust manifolds to the cylinder heads get thread sealant and torqued in 2 passes. First pass-11 lb/ft, second pass-18 lb/ft. Starting in the center then alternating outwards.

The nuts on the studs get tightened to 37 lb/ft with no mention of a thread lubricant or thread locker
 

Joel K

Supporter
Hi Ken, I may have asked the question incorrectly. Looking to attach the oval exhaust down pipe flange to the outlet on the exhaust manifold. These have four studs and nuts each.

E621E311-C5F1-47E3-B7A6-7D4E21F33143.jpeg
 

Ken Roberts

Supporter
Those are the ones I have. The GM part number is #11518424. They sell for about $10 each new.:oops:

The matching nuts are #11517996. They sell for about $4 each new. They are distorted thread lock nuts so I would recommend buying new. I would just use regular m10x1.5 nuts for fit up and then swap over to the distorted thread nuts when assembling for final time. I wouldn’t install the gaskets until final fit up as they are a one time use “crush” gasket.

You could even just buy distorted thread flange nuts from McMaster Carr. The stock nuts are not stainless. The studs are stainless.
 
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dito on the mock up fasteners and ant-seize

Id use stainless. Thats what i'm using.
Dont use ebay or no name stainless fasteners for applications where a broken stainless bolt could be a problem. I'd go with ARP or factory for bolts in this application. I wouldn't even use mcmaster for this. Poor stainless bolt quality is problematic (ive made that mistake). ARP makes some nice stainless studs for the ls. im using them.
 

Joel K

Supporter
dito on the mock up fasteners and ant-seize

Id use stainless. Thats what i'm using.
Dont use ebay or no name stainless fasteners for applications where a broken stainless bolt could be a problem. I'd go with ARP or factory for bolts in this application. I wouldn't even use mcmaster for this. Poor stainless bolt quality is problematic (ive made that mistake). ARP makes some nice stainless studs for the ls. im using them.
Thanks Dusty, I have been using short 10mm flanges hex nuts for the mock up.
 

Joel K

Supporter
The 6 bolts holding exhaust manifolds to the cylinder heads get thread sealant and torqued in 2 passes. First pass-11 lb/ft, second pass-18 lb/ft. Starting in the center then alternating outwards.

The nuts on the studs get tightened to 37 lb/ft with no mention of a thread lubricant or thread locker
Ken, just to clarify. The 6 bolts are for the manifold to the engine. If I removed them, you’re providing the instructions to torque them back on. At this point I haven’t touched them.

The studs on the flanges get tightened, and the nut gets torqued to 37 lb/ft which I assume also tightens the stud to the proper torque.
 

Ken Roberts

Supporter
That’s correct Joel. Although these torque measurements are for the LS7/LS9 manifolds and LS3/LS7/LS9 cylinder heads. I’m sure the LT4 is the same.
 
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