Torqueing Exhaust Studs?

I'll be installing new exhaust studs soon. In the past, I've screwed the stud into the head with a torque wrench to the same torque called for on the nut.

It didn't seem right, the non-threaded part of the stud went in deeper than it looked it should, as well, it never seemed that it was going to pop the torque wrench, several times I've given up and left it partly torqued.

I really haven't seen much reference to actually screwing the stud into the head.

Are you supposed to torque the stud to the same torque as the nut?

OR

Are you supposed to screw in the stud so the non-threaded portion is flush with the flush with the head surface?

Generally, you are supposed to torque the stud in to the same value you use on the nut. In practise (and in low-preload applications like this,) you can just turn the stud until it "bottoms out" on the shank, and then turn it an additional quarter-turn or so so it won't loosen.

The torquing of bolts is not only to assure a fairly even clamping load, but to "preload" the bolts so there is resistance to undesired turning (read: loosening.)

I'd also suggest using LocTite #272, and only #272, on the threads of all the fasteners. If you can't get #272, don't bother with anything else - it won't stand up to the heat.

If you cannot get #272, you might want to consider never-seez - but be sure to reduce installation torque by half if you do use it (to account for the lubricity of the compound.)

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LocTite #272? That worries me. I have Red Loctite, but I'm not sure if its #272 or not.

The studs come with a yellow compound already applied and dry on the threads, I'm assuming they are some sort of loctite compound.

These studs break off easy enough already, I worry red loctite would just increase the chances of breaking another one, in case I ever have to pull the manifold again.

I was sure as too use loctite or anti-sieze, eitherway, I planned on using something to combat the siezing these bolts are prone too. I figured the compound applied to the studs was some sort of locktite, that I'd just add a little extra BLUE Loctite to cover the couple of threads not covered by the pre-applied compound. Guess your saying the BLUE is worthless in this case because of the heat.

LocTite #272 is roughly equivalent to #242 in strength, but is formulated to handle exhaust heat. It will be fine, and it "breaks" at about the point that LocTite #242 does. (Sorry, but I remember them by number. I believe the "blue" LocTite is #242.)

If you have trouble with stud breakage, go get some 3/8"-16 brass allthread rod, and make new studs out of that. Brass won't sieze against the iron, and it won't lose strength with repeated heating/cooling cycles like steel does. I've been using brass hardware for exhaust fastening for a number of years now. I also use either silicon bronze or brass bolts for the rest - you can order those from Fastenal, or find them at better marine/boating supply stores. Get 3/8"-16 x 1-1/4" bolts, no need for an exotic head.

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