dlr944

Anyone know the torque spec for installing the exhaust stud for 89 951?

johne

Hmm, very good question seeing as I'm going to be installing 8 of them around noon tomorrow.

Perry 951

Double nut the stud and torque to 15ft/lbs.

johne

Thanks Perry,
Man I might as well just cut out the middle man and start PMing my questions strait to you.

5speed300

What is the process for installing the studs into the head? I want to avoid tightening them into the head further than they are supposed to go but I'm not sure how to install them.

I have studs with an allen head insert on the end so its easy to screw them in. Do I just screw them in until they stop (finger tight) and then install the nut and torque the nut to 15 ft/lbs. Or do I install the stud and torque it to 15 ft/lbs, and then also torque the nut to 15 ft/lbs?

Bri Bro

You want to tighten the stud so it doesn't come out with the nut the next time you take off the headers. You can just tighten the stud in by hand but you will be taking off the stud and nut the next time you take off the header. Just do what Perry said above, hand tighten the stud and double nut the end of the stud, then torque it to 15ftlbs and remove the nuts. Over time, the stud will set into the head and require more then 15ftlbs to remove it. Use anti-seize on the threads before you put on the nut for the final assembly.

toyhole

I asked the same question to Clark's Garage about the stud torque. He told me to just finger tighten and use locktite if I was worried about them backing out. Otherwise, He said I was risking breaking/having the studs pull out due to the heat cycling.

Joe Jackson

I would never torque a stud on its own. Studs don't have a definitive stopping surface like a bolt or nut does. The unthreaded section of the stud is tapered where the rolled thread ends. This taper helps lock the stud into the tapped hole but forcing the stud into the hole could easily damage at least the first few threads making future R&R difficult. Some studs use an slight interference thread to help keep them from backing out.

I've always installed studs either by hand until they stop or by using a prevailing torque lock nut (like the factory Porsche hardware). I've never had one back out.

As for the studs coming out with the nut, unless you pull the cylinder head with the manifolds attached, you need to remove most of the studs anyway to get the manifold out of the car. The stud coming out with the nut simply saves a step. Use a small pipe wrench on the unthreaded section to grip the stud and remove the old nut. Preferably use a new locknut for reinstalltion, or double nut it to help bottom the stud.

Wow, old original post. Should have checked before responding.