Hi All –
Getting ready to order new exhaust studs for the 6 conversion. I need to measure the flanges on my headers, then make the call. Anything to stay away from in terms of stock vs stainless, etc etc etc?

Aren’t they just M8-1.25’s? I know even my local Ace Harware had them in various lengths – but I don’t know what they were made of.


Thanks!!!
Scott S

I do know stock 911SC and later exhaust flanges are just shy of 1" thick, though that requirement may change depending on what kind of exhaust you run.

As for hardware most 'automotive,, studs available at hardware/automotive stores are designed for general auto use and will work for those uses. For hi temp make sure they are the same grade or better. But of course one should always get the best one can find and or afford.

General stainless tip; Do not use stainless nuts on stainless bolts, they will eventually if not imediately gall/seize. Especially under higher torque.

NEVER use stainless fasteners for exhaust applications! There are embrittlement issues that will make you VERY sorry. I recommend OE replacement studs and the stock nuts. You'll need a set of 8mm flat washers, as well. I wouldn't buy them from your local FLAPS or hardware store. You have one break off and you'll have a mess on your hands. You probably don't own the drill fixture needed to do the repair in the car.

The Cap'n

Thanks Cap'n - Stock it is!!
Yep, I have that fixture. It worked like a champ on the two broken studs I had to remove. Best money I have spent on this project so far!.

Thanks again -

A little late to this one. Yeah Scotty, steel M8x1.25

Click to view attachment

Link- (Car Parts Dicount) to genuine OEM Exhaust Manifold Studs..

http://www.carpartsdiscount.com/auto/parts...tml?3593=101653

No on the Stainless, No on the Hardware store.

My experience when I had issue with the studs on my orginal cylinder heads that the PO had "repaired stripped threads and replaced studs with Non-OEM" and ended up with rebuilt cylinder heads that the rebuilder used Stainless Studs only to remove the stainless studs and install OEM..

None of the replacement studs that are stainless or ? are the exact same measurment or desighn as the OEM.

There can be a variety off unsuspecting issues with using non-oem studs..

And this is an area that can be expensive to repair and the issue with using non-oem may not show itself imeadiately but will over time..

One stud failed and It cost me over $1,000 easily to remedy... Your repairs may vary...

Most damage is done removing rusty nuts. The old chevy fix was to use brass nuts on good studs orrrr use a nickle high temp anti-sieze on steel nuts and a torque wrench on lubricated nuts.