Exhaust Manifold Stud Length?

[Patrick N.]

Does anyone know the length or type of stud I need for BB manifold to connect the exhaust tube? I am hooking up my Gardner exhaust to the manifold and ran into an issue_ on the driver side the 3 studs on the bottom of the exhaust manifold used to connect the pipe flange are way too long.

I have assembled the doughnut + inner pipe inserted in the larger exhaust tube and BB flange. When I put the flange on the studs, the smooth section of the studs are showing in the exact spot that I need threads.

Thanks
Pat

[Patrick H.]

Re: Exhaust Manifold Stud Length?

There are 2 lengths of studs. The longer ones go on the right (passenger's) side to account for the heat riser taking up space. The shorter ones go on the left (driver's) side. I would suspect that someone put the wrong ones on the left hand manifold of your car. You might be able to remove and replace them with the manifold still on the car. Replacements are available at almost any auto parts store, though I personally like the stainless ones to avoid having them rust out or seize. Here you go: https://www.paragoncorvette.com/p-35...-stud-kit.aspx

[Patrick N.]

Re: Exhaust Manifold Stud Length?

Thanks Patrick, The car had side exhaust when I got it and both sides are the long studs. I agree, I'll do SS as well since these are such a PIA to remove when rusted to the manifold.
Thanks again,
Pat

[Rob M.]

Re: Exhaust Manifold Stud Length?

There are 2 lengths of studs. The longer ones go on the right (passenger's) side to account for the heat riser taking up space. The shorter ones go on the left (driver's) side. I would suspect that someone put the wrong ones on the left hand manifold of your car. You might be able to remove and replace them with the manifold still on the car. Replacements are available at almost any auto parts store, though I personally like the stainless ones to avoid having them rust out or seize. Here you go: https://www.paragoncorvette.com/p-35...-stud-kit.aspx

Hi Patrick,

Any tips on how to get them out (especially when the exhaust manifolds don't be removed)? any special tooling available to get this job done easily?

[Patrick H.]

Re: Exhaust Manifold Stud Length?

I've used Grade 8 nuts, and you have to double them up against each other, using the upper one as the one to turn with your wrench.
The lower one, if they are tightened against each other enough, acts like a "stop."

If this doesn't work you then remove the manifold, bring it to someone with a torch to heat it up and remove it. I've used a machine shop.

[Jeffrey S.]

Re: Exhaust Manifold Stud Length?

I have used a single nut by cutting through one flat with a hacksaw. Run the nut onto the stud and use a vice grip on the nut. The nut protects the threads and clamps tightly to the stud. Of course if it is rusted in, only a "heat wrench" will work.
Jeff

[Patrick N.]

Re: Exhaust Manifold Stud Length?

I've used Grade 8 nuts, and you have to double them up against each other, using the upper one as the one to turn with your wrench.
The lower one, if they are tightened against each other enough, acts like a "stop."

If this doesn't work you then remove the manifold, bring it to someone with a torch to heat it up and remove it. I've used a machine shop.

FWIW, The double nuts technique works well, I removed two last night with the nut technique- the last one will need heat and some Kroil or candle wax to help it out.

[Rob M.]

Re: Exhaust Manifold Stud Length?

I have used a single nut by cutting through one flat with a hacksaw.

Hi Jeff,

I'm not fully understand what you mean with this way of working, could you take of photo or make a small sketch of this solution?

[Jeffrey S.]

Re: Exhaust Manifold Stud Length?

Rob,
Attached is a photo of a nut marked with the cut line I referred to. Once the nut is cut, the space created by the kerf of the saw allows for the nut to clamp tightly to the bolt/stud when using a vice grip. Hope this helps.
Jeff

[Rob M.]

Re: Exhaust Manifold Stud Length?

Rob,
Attached is a photo of a nut marked with the cut line I referred to. Once the nut is cut, the space created by the kerf of the saw allows for the nut to clamp tightly to the bolt/stud when using a vice grip. Hope this helps.
Jeff

Now I get the picture :-) I will use this method and let you know the outcome! I have 6 studs to get out...

[Terry M.]

Re: Exhaust Manifold Stud Length?

My experience, not necessarily on Corvettes but they are all the same, leads me to reach for the hot wrench and not waste my time and effort on items that I will replace anyway.