Header bolts

[kennythewelder]

I have to respectfully disagree with grade 8 or hardened bolts in exhausts. If it rusts through and breaks, you're going to have a devil of a time extracting it. As I said in another post, feel free to ask my how I know. The clamping force necessary to attach your exhaust is easily within the limits of grade 5 hardware.

I wonder if a lot of the issues with header bolts breaking is because people improperly use exhaust hangars. You don't want the exhaust swinging around, but you do want some give in the hangars to allow for engine torque. If a sideways force is repeatedly applied to the bolts they won't last long, even if they are grade 8.

The issue with grade 5 bolts, is that they are to soft to torque up to the extreme force it takes to clamp headers. The mild steel that the header flange and tubes are made of expand and contract much more that cast iron exhaust manifolds do, that have very little expandtion a contraction. This warrants extreme clamping force to get and keep a good seal that is not needed on a cast iron manifold. Also chances are, your going to have to replace header gaskets every few years. About 2 to 3 years is about as long as I get out of my gaskets, and I have tried every brand header gaskets they make. My best results have been fel-pro header gaskets with over torqued bolts. I have rounded over the small grade 5 header bolt heads torquing or removing them. Again as I said before, I drive my truck every day. This does help the rust factor. As for a stuck bolt, I deal with that almost every day at the shop. I weld a nut over the broken stud. Once the nut cools off, 90 percent of the time, the heat from welding loosens the stuck bolt once it has cooled off, and is easy to remove. The other 10 percent of the time, the bolt has to be machined out of the hole, or in this case, yes it would need to be drilled and have the threads chased, but I would use heat on the head around the bolt hole first. We all have our own way of doing things, and I am a welder after all, so I use what I know. Only giving my logic on why I choose grade 8 header bolts over grade 5. Also I have had to use vise grips to remove rounder over heads on grade 5 header bolts to remove them. Never on grade 8 header bolts.

 

[Redneckgeriatric]

I have to respectfully disagree with grade 8 or hardened bolts in exhausts. If it rusts through and breaks, you're going to have a devil of a time extracting it. As I said in another post, feel free to ask my how I know. The clamping force necessary to attach your exhaust is easily within the limits of grade 5 hardware.

I wonder if a lot of the issues with header bolts breaking is because people improperly use exhaust hangars. You don't want the exhaust swinging around, but you do want some give in the hangars to allow for engine torque. If a sideways force is repeatedly applied to the bolts they won't last long, even if they are grade 8.

yeh, headers are always moving. cast iron moves too. you can see chaffe marks. i appreciate your argument, but if you break any bolt in the head, its gonna be a pain to extract. the plan is to not break (twist) a bolt in the first place. chinese bolts these days may not be as hard as you think, and proboably not any heat treating, so they anneal easy, stretch, loosen headers wiggle them back and forth, they gall, they break. look at reace cars and no longer wonder why they use never sieze and safty wire. and grage 8 bolts with allen heads. (easier to drill).

 

[Tim W]

Ok guys Im slow.... so yall are saying these bolts are a bad idea? https://www.summitracing.com/parts/arp-400-1201/

 

[kennythewelder]

If you use them,make sure to use some anti-seize for headers or for exhaust bolts.

 

[Tim W]

And the anti seize won't make the bolts back out?

 

[kennythewelder]

No, as long as they are torqued down. Grade 5 is about 30 FLBS and grade 8 are 44 FLBS. This is why I rather grade 8. Also after you drive the truck for 10 or 15 miles, you will need to retorque the bolts. Some of the bolts are very hard to get to with a torque wrench and socket. For these, I use a wrench and a cheater pipe. I have bent a wrench before torquing header bolts. That being said, I think its been about 3 years since I last replaced header gaskets. I know its been over 2 years for sure.

 

[CrustyJunker]

I will say this, ARP stainless steel is not the same kind of stainless as your 316 grade stuff from the hardware store. It's significantly harder. If I had iron heads, I think I'd like to try them.

I've used stainless ARP bolts in quite a few other applications, but I have not personally used them in a header application yet. I have used general-duty stainless bolts many times on collectors (both ball and socket/3-bolt flanged) without issue. Most of my vehicles with headers have aluminum heads, I was afraid to try stainless in those applications. One vehicle with iron heads I had studs with a few bolts where there wasn't clearance. They were inevitably rusty, too.

I vouch try them and let us know how it goes!

 

[dave s]

I've had the stainless 12 point ARP header bolts in iron heads on my old Nova since 2003. I had used the Percy soft aluminum gaskets. I know at first I had to retorque them a couple times. After that, no issues since. I just went down to the garage and uncovered the front and put the hood up and pulled a 12 point ARP stainless bolt out. Hasn't been removed since motor was put together in 2003. Came right out. Not sure if I used anti seize or not. Can't remember. Checked several others and still nice and tight.

 

[Spookers]

Ok guys Im slow.... so yall are saying these bolts are a bad idea? https://www.summitracing.com/parts/arp-400-1201/

Yes those will work great, I believe the flange on the head is serrated so it won't back out, if not and you're worried lock washer it assuming you have enough thread engagement to do so. Personally I dont use lock washers as I haven't had an issue with them backing out.

Just a word of advice, Chase all the holes and use never seize (copper if you can) and if gaskets are an issue I personally like MLS gaskets from felpro but they don't allow for much warpage. And if you need to "over torque" your bolts to get it to seal you have a warped header that needs to be planed. (Every header I've ever bought was always warped a little, probably would have worked for a while but I'd rather not chance it, had headers on for 6years no issues)

 

[Tim W]

Yes those will work great, I believe the flange on the head is serrated so it won't back out, if not and you're worried lock washer it assuming you have enough thread engagement to do so. Personally I dont use lock washers as I haven't had an issue with them backing out.

Just a word of advice, Chase all the holes and use never seize (copper if you can) and if gaskets are an issue I personally like MLS gaskets from felpro but they don't allow for much warpage. And if you need to "over torque" your bolts to get it to seal you have a warped header that needs to be planed. (Every header I've ever bought was always warped a little, probably would have worked for a while but I'd rather not chance it, had headers on for 6years no issues)

Thanks. I am going to try them out. By chasing the threads you mean run a tap in the bolt hole? Is that to just clean them up from rust and crud? Its ben 15 years or more since iv installed headers.