Bolts Instead of Studs For Exhaust

[eckoxl]

Anyone use bolts instead of studs for exhaust manifolds? Just asking because I can't find any studs locally, but I can find bolts. If so, how long should they be? I know the thread is M8x1.25.

[fastback4]

I've thought about this swap also. Can't say i remember anyone talking of doing the swap. I know the nuts used on the exhaust studs that are on the heads are locking type nuts, so i suppose alot of exspantion/contraction is going on between the aluminum head and the cast exhaust. I have some metric bolts ( M8x1.50) i may use but i'll apply some thread locker to them first......

[geoffinbc]

Your auto parts store should have a selection of studs. At least the ones around here do. Or have you tried a GM dealer to get stock replacements? I bought all new ones for my engine and they were cheap.

Try gmpartsdirect or rockauto also

[Azrael]

My local dealership was asking $20 per stud. They obviously didn't need anyones business. If you do use bolts, make sure you use those split lock-washers.

[geoffinbc]

Lock washers wont to anything for exhaust bolts. It's too hot and they loose their temper. They wont prevent the bolts from backing off. The best way to prevent exhaust bolts from backing off is to drill a small hole through the side of the bolt head and wire them in place.

[pocket-rocket]

The 4.3 TBI I changed in a 4x4 Jimmy had bolts. It also had these little flimsy sheet metal hoops that went over the top of the manifold ports between the two bolts. It also had ears on it that got bent over the sides of the bolts once they were honked down on to keep them from rotating out.

[geoffinbc]

Yea they work well too.

[96lumina]

Let me add a little warning about removing studs and using bolts in a aluminum head...I don't advise this swap...with a soft material like aluminum the stud is screwed in and stable while the nut does all the force to cinch the manifold against the head...if you remove the stud and use a bolt you are now going to rely on using the threads in the softer aluminum head to tighten the manifold against the head...what this will do is gull the threads and eventually it will strip out...you might say that the first time it worked fine, but in reality you probably already did the damage and don't know it yet...this is why all aluminum heads have studs, it is the most effective way to hold parts together but if you do use the bolts, then best of luck to you and don't say I didn't warn you not to do this swap...I don't advise it!

if you must have the bolt look then what I would do is cut your studs to length and use some of those SS nuts that are domed to cover the stud this will give you a cleaner look and you will keep your studs...I believe there is a kit that has a center allen head to install the stud...but this is the only safe way of not damaging your head.

[fastback4]

That is sound advise. I believe I'll use the studs and nuts....Thanks 96

Let me add a little warning about removing studs and using bolts in a aluminum head...I don't advise this swap...with a soft material like aluminum the stud is screwed in and stable while the nut does all the force to cinch the manifold against the head...if you remove the stud and use a bolt you are now going to rely on using the threads in the softer aluminum head to tighten the manifold against the head...what this will do is gull the threads and eventually it will strip out...you might say that the first time it worked fine, but in reality you probably already did the damage and don't know it yet...this is why all aluminum heads have studs, it is the most effective way to hold parts together but if you do use the bolts, then best of luck to you and don't say I didn't warn you not to do this swap...I don't advise it!

if you must have the bolt look then what I would do is cut your studs to length and use some of those SS nuts that are domed to cover the stud this will give you a cleaner look and you will keep your studs...I believe there is a kit that has a center allen head to install the stud...but this is the only safe way of not damaging your head.

[Azrael]

Would heli-coiling be recommended? I don't see why not as almost everything on aircraft engines are.

[WrathOfSocrus]

The rocker arm bolts are installed with more torque than the exhaust manifolds and they compress a valve spring up to a few thousand times per minute for hundreds of thousands of miles. The dogbone mounts are bolted down with a lot more torque and keep the engine from flopping around. I'm pretty sure they used studs because you can slide the gasket and manifold on and hold it in place with one finger while installing the nuts to tighten them down, instead of fumbling with the gasket as you install bolts. Useful for the assembly line and home mechanic alike.

That being said, I ordered long stainless steel set screws along with stainless hardware in hopes of preventing corrosion. I got them from boltdepot.com. The shipping was about as expensive as the parts. If you have other bolts you are looking to replace that you can't find locally, it is worth the time to figure out what you need and make one order as opposed to overpaying on shipping twice.

[96lumina]

Would heli-coiling be recommended? I don't see why not as almost everything on aircraft engines are.

You could heli-coil all your holes yes...but first you will have to remove your heads so you can have a machine shop enlarge all the holes and retap them so after the heli-coil is installed they will be the same size stud you have now...if you just heli-coil the hole you have you will end up with a much smaller stud that will not be suffecient enough to handle the heat/cooling cycles...I also believe that the "aircraft" heli-coil is a much different application then the repair jobs you buy down at the store...all aviation work is highly monitored and recorded by engeneered specialists...the process they use and the type of material to install their heil-coil is way different then what you buy down at your local auto parts store...all I can say is it's your car, so you can do what ever you want to it.

[mickaz]

I did this on my quad 4 head that was allready installed. You just have to have a Drill and a drill bit to the right size of the helicoil and you install it with the tool and voila. the helicoil is going to be 10x stronger then the old threads you had anyways.

if the studs dosent break the aluminum thread, they wont certainly break a helicoil.

[96lumina]

I did this on my quad 4 head that was allready installed. You just have to have a Drill and a drill bit to the right size of the helicoil and you install it with the tool and voila. the helicoil is going to be 10x stronger then the old threads you had anyways.

if the studs dosent break the aluminum thread, they wont certainly break a helicoil.

So how you gonna do the rear head?, and to do the front you will have to remove the radiator...A quad is a whole different ball game...do one first on a V6 car, then recommend a V6 owner to do theirs...there's not a lot of room for a drill let alone one with a 5" drill bit attached...come on! use your head...no pun intended, LOL...I'm fairly familiar with the quad 4 and can say your motor sits straight up and you have a ton of room for a drill and bit to do what you need done...and willing to bet you fixed some one else's header bolt install cuz you had a bunch of stripped holes when you bought your car, just a guess.

[Rootie524]

dont know if this has already been covered since i briefly skimmed through this but zzperformance.com sells exhaust studs for about $1.00 a piece with antiseize or threadlocker (i foget which one) already on it. much better deal than the stealership.