Exhaust manifold stud removal advice?

[Turbocoupe75]

The stock studs aren't "high tensile" but are different than the standard studs off the shelf from your local hard ware store.

[BAD 44u]

i used stainless allen key bolts and could never get the exhaust gasket to seal properly put new studs split washers and nuts and its perfect now. if you do use bolts they have to be the exact length to long they wont torque up to short you'll stuff the thread like i did on one.

[Rodeobob]

Stainless cap heads maybe but theres no way i would be using stainless button heads.

Stainless bolts are soft, softer than grade 4 bolts, i have used a few stainless button heads on my bike for fixing the pannier brackets to the side and the heads deform in the allen key hole before they are tight enough form my liking.
Cap heads are also thread all the way to the head.


I would say use cap heads. Dont measure the totall length you need, measure the length of shank you need. Thats the unthreaded bit below the head. Measure the manifold etc that your bolting on and get some bolts with a shank a little bit shorter than the manifolds thickness. having the shank allows for a positive location of the manifold and you wont have any thread ware issues should the bolt come loose.


You can also get the higher grade cap heads in zinc plated, thats probably a better option. Or get black ones and have them plated.


And as has been said, always use antiseize on stainless bolts going into aluminium, be sure and put some under the head of the bolt as well as the threads.


Bob.

[smokey]

gee so many replies im a little confused now.Many of them are common sense and im sort of leaning toward dome nuts now for a decent look but a proper performance point as well.Im still pushing decent power with this engine and even though its "hairstyle" a the moment eventually its going to get thrashed again on the dyno and track,i really need to keep that in mind also,so after reading the replies being able to properly retorque the studs properly is quite high on my priority list now!!

[PSIGEM]

Friend has allen key headed bolts in his Gemracing motor with gemracing manifold and disco potato, just sent the car to have exhaust, ecu and cooler pipes fitted then tuned so will see how that goes

[Greengem20B]

AAAArrhgg, never never use stainless steel bolts in alloy, they cause a "galvanic reaction between the screw and aluminum takes place that promotes corrosion" The same goes for stainless steel helicoils into aluminium.

Chroming bolts or using stainless steel bolts that are exposed to heat and expansion is a big no no as well (for extractors or turbo's especially).

Great for a show car but be careful for a performance or structural application. Stainless bolts are used where corrosive chemicals or water are involved, not as a shiny replacement to a high tensile bolt.

You can use Devcon for the Ally/SS combo..its designed for all dissimilar metals - Messy though

304SS is generally used for exhaust applications....though Ive had 316SS bolts in a motor for years with no problems.

But as above, I wouldnt use SS anywhere on the undercarriage/drivetrain.