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stock 6 bolt head studs strength

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rtincher22085

10+ Year Contributor
140
0
Aug 17, 2010
Rockland, Maine
Are these stretch studs like the 7 bolt according to a thread I just read.

They were also said to be as strong as the ARP replacement is this correct? I have a set lying areound with 80K on em is it a good alteranative to spending 80bucks or just spend it. i don't plan on running more than 18-20 psi on a E316g. 8.5:1 compression
 
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18-20psi is no problem, even on used 6-bolt studs. However I don't think that they'll fit in a 7-bolt, but I may be wrong. And to answer your question, "no", they're not torque-to-yield bolts like the 7-bolt studs are, so you can re-use them (according to Haynes).

Also I know that our 6-bolt headbolts are the same as the ones used in 3000gt VR4s, and those guys have ran 9s on stock headbolts.
 
To be safe I would get the arps. The 6-bolt bolts are stretch bolts. I have blown head gaskets from reusing stock bolts. I leared years ago to just throw away the bolts and either buy new ones or get the arp's
 
To be safe I would get the arps. The 6-bolt bolts are stretch bolts. I have blown head gaskets from reusing stock bolts. I leared years ago to just throw away the bolts and either buy new ones or get the arp's

The 6-bolt head bolts are not torque to yield like the 7-bolt bolts. I have run 30+ psi on 6-bolt stockers. They are almost 2MM larger than the 7-bolt bolts at the shank.

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yeah man i would spend the 80bucks i made the mistake of reusing head studs :ohdamn: so the second time around i spent the 80 bucks well worth it man!!
 
Thanks for the info guys. I should have just said I wasn't running high boost is it ok to reuse the stock 6 bolt studs. I pretty much got my answers from the top dsm posters. Pretty much what I was looking for. I know they were thicker and shorter meaning stronger. thinner and longer means streching. i have reused honda head studs and they are longer than the 7 bolt anf thiinner but it also isn't forced induction either. Just had to make sure.

yeah man i would spend the 80bucks i made the mistake of reusing head studs :ohdamn: so the second time around i spent the 80 bucks well worth it man!!
Did you clean the mating surfaces 100% and torque them down to spec? did you use a scotchbrite to clean the head and the block(elbow grease) 75 % of head gasket failure is due to improper installation process cleaning, straightness, and what caused the failure in the first place. I have my block machined and my head so I thinkfrom what I've heard I will save the 80 bucks.

To be safe I would get the arps. The 6-bolt bolts are stretch bolts. I have blown head gaskets from reusing stock bolts. I leared years ago to just throw away the bolts and either buy new ones or get the arp's
From what it looks like you own all 2g's and deffinetly I would buy them in a heart beat if I owned a 7 bolt. But I ain't planning on making 700 hp. according to some in info below I can handle 30+ thats if everything is 100% when I reinstall them. i'll be running half that.
 
From what it looks like you own all 2g's and deffinetly I would buy them in a heart beat if I owned a 7 bolt. But I ain't planning on making 700 hp. according to some in info below I can handle 30+ thats if everything is 100% when I reinstall them. i'll be running half that.

What you fail to realize is that I have owned 6 1gs 3 with the 6-bolt. I have two 6-bolts on the floor in my garage. One is out of a 2g I own. I have owned over 10 mitsu cars only took one car for me to learn about Mitsu head bolts. After changing the head gasket 3 times in a week due to head bolts. I was baffled at first.

I worked at a Chrysler dealer and was looking up factory specs on head bolt reuse. There was not specs in the factory manuals. Started asking around the shop and tec's were saying you can reuse them up to three times. But I was having issues even after the second use.

So this is why I all ways recommend changing from stock bolts to studs. Especially if you do not know how many times those bolts have been reused.
 
If you have to ask this, expect to be bitched at for not going out and buying brand new head-bolts for your head. Here are a couple of facts.

1 : The 6 Bolt Head Bolts are NOT torque to Yield, which means unlike the 7 bolt head studs, they are not meant to stretch when torque is applied.

2 : The 6 Bolt Head bolts are usable in a 2G, save for the fact that the holes in the head on a 2G are a bit smaller. These have to be widened out a bit to allow the bolts to slide through.

3 : It is POSSIBLE for 6 bolt head bolts to stretch, but they are not MEANT to. You can take them out and measure them, see if they are still in spec. If they are stretched even a little then throw them out and get new ones.

4 : When asking questions like this, be prepared for harsh responses in regards to your questions based on the idea that you can reuse something and save money. In the end, it's up to you. If they check out after measuring them, I'd reuse them as I have before with no issues. If they are not up to spec, get the ARPs and you'll never have to worry about it again.

If someone has reused 6 Bolt Head Bolts and blown a head gasket, it's because they either didn't measure them to ensure they were okay, apply the torque sequence correctly, or simply neglected to do some other small thing. 6 Bolt Head Bolts Are reusable as long as they are still within spec.
 
If you have to ask this, expect to be bitched at for not going out and buying brand new head-bolts for your head. Here are a couple of facts.

1 : The 6 Bolt Head Bolts are NOT torque to Yield, which means unlike the 7 bolt head studs, they are not meant to stretch when torque is applied.

2 : The 6 Bolt Head bolts are usable in a 2G, save for the fact that the holes in the head on a 2G are a bit smaller. These have to be widened out a bit to allow the bolts to slide through.

3 : It is POSSIBLE for 6 bolt head bolts to stretch, but they are not MEANT to. You can take them out and measure them, see if they are still in spec. If they are stretched even a little then throw them out and get new ones.

4 : When asking questions like this, be prepared for harsh responses in regards to your questions based on the idea that you can reuse something and save money. In the end, it's up to you. If they check out after measuring them, I'd reuse them as I have before with no issues. If they are not up to spec, get the ARPs and you'll never have to worry about it again.

If someone has reused 6 Bolt Head Bolts and blown a head gasket, it's because they either didn't measure them to ensure they were okay, apply the torque sequence correctly, or simply neglected to do some other small thing. 6 Bolt Head Bolts Are reusable as long as they are still within spec.

Well Said Bro, I am new to DSM, but not new to rebuilding engines. So When I started rebuilding a 6 bolt 1G for my starquest, I was wondering, should I or can I reuse my stock head bolts! Well I knew they were not torque to yield so I figured I would get them measured to make sure they are still within spec...thanks for solidifying my thought process!

And rtincher22085, thanks for starting this topic, I had the same question, but didnt want to ask due to getting ridiculed! LOL I mean its not your fault, this is posted in the Newbie section right? thats what Newbie sections are for!

so thanks everyone for the input! this really helped
 
yeah man i had my head decked nd block sanded but when we tourqed the head studs. i dont think we used the right pattern.... and also we didnt re-tourqe the studs after the break in period....:banghead:
 
yeah man i had my head decked nd block sanded but when we tourqed the head studs. i dont think we used the right pattern.... and also we didnt re-tourqe the studs after the break in period....:banghead:

The Pattern is to torque from the inside out. Then outside in, and then inside out in a cross pattern. 3 Passes at 30 LBS each. That's how I've always done it and I've never had an issue.

I Also re torque after 50 miles, and 500 miles.
 
If you have to ask this, expect to be bitched at for not going out and buying brand new head-bolts for your head. Here are a couple of facts.

1 : The 6 Bolt Head Bolts are NOT torque to Yield, which means unlike the 7 bolt head studs, they are not meant to stretch when torque is applied.

2 : The 6 Bolt Head bolts are usable in a 2G, save for the fact that the holes in the head on a 2G are a bit smaller. These have to be widened out a bit to allow the bolts to slide through.

3 : It is POSSIBLE for 6 bolt head bolts to stretch, but they are not MEANT to. You can take them out and measure them, see if they are still in spec. If they are stretched even a little then throw them out and get new ones.

...

If someone has reused 6 Bolt Head Bolts and blown a head gasket, it's because they either didn't measure them to ensure they were okay, apply the torque sequence correctly, or simply neglected to do some other small thing. 6 Bolt Head Bolts Are reusable as long as they are still within spec.

Just to add:

1: Agreed, 6-bolt head bolts (HB) are not torque to yield. However, like any other fastener that has a torque value, the bolt will stretch. The difference between a 6-bolt and 7-bolt HB is that the 7-bolt HB will experience stress beyond the material's yield point, meaning it will plastically deform/permanently stretch and land outside specifications. A 6-bolt HB will typically deform elastically, meaning it does not stretch permanently or experience stress above its yield point and it will return to its original length. As the bolts stretch plastically, they harden and become brittle making them easier to break or otherwise fail (loosen, etc.).

2: Yes, 6-bolt HBs can be used with a 2G head by opening up the bolt holes and it is absolutely acceptable to do so. They cannot be used in a 2G block without re-drilling and tapping the head bolt holes in the block; this is not usually an option for everyone.

3: If a 6-bolt HB shank has stretched at all from its original length (84mm), they should be replaced; I say this because I do not find a max limit specification for a 6-bolt HB elongation, but surely fractions of a millimeter won't hurt. That much is up to the owner's discretion in my opinion. I tend to reuse my 6-bolt HBs without much thought in the matter and have yet to experience any problems. A 7-bolt HB shank is 97mm originally and should be replaced if they exceed 99.4mm.
 
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Get the ARP"s. It will be a lot better and you will also feel a lot better knowing you have them for insurance. Plus in the future, Im sure you will upgrade your turbo, and run higher boost than you plan on now. Do it right.
 
yeah i went inside out but i double checked it like... 30 ft. lbs first and then to the requiered tourqe if i remember 85ft. lbs for arp's?? it was a while ago when i had my 1gb:aha:
 
yeah man i had my head decked nd block sanded but when we tourqed the head studs. i dont think we used the right pattern.... and also we didnt re-tourqe the studs after the break in period....:banghead:

thats interesting, I have never been aware of Re-Tourqeing after the break n period! Im glad you threw that out there, ill be sure to do that as well! after mine gets broken in...Since were talking about it, On this motor whats the usual break-in period? is it 500 to 1000 miles like most engines? Just curious!
 
thats interesting, I have never been aware of Re-Tourqeing after the break n period! Im glad you threw that out there, ill be sure to do that as well! after mine gets broken in...Since were talking about it, On this motor whats the usual break-in period? is it 500 to 1000 miles like most engines? Just curious!

Break-In is a heavily debated process. Google Motoman's breakin method for more information. That's what I followed and it's worked well for me so far.
 
I asked this question beacause:
1. I want to save money.
2. They are out of my car at 80k (never overheated)
3. I'm not planning on running 10 seconds
4. To see if the info I read was correct

Thanks for the in depth Info guys. You are all wise and full of knowledge Mad Props :thumb:
 
Break-In is a heavily debated process. Google Motoman's breakin method for more information. That's what I followed and it's worked well for me so far.

dude thats sweet! It actually all makes sense! I cant wait to try it out! thanks a lot!
 
Break-In is a heavily debated process. Google Motoman's breakin method for more information. That's what I followed and it's worked well for me so far.
I think like motoman says the first 20 miles is criucial. Get on it hard after its at operating temp and deccellerate back down to say 20 then back on it then drive it moderatly for the first 500 after changing the oil, after the first 20-50 miles. If its forced induction alot of exerted forces are on thes babies so if you don't seat them good you loose the potential power. Hard first 20 miles give or take then moderate after 500- 1000 you choose. Then all out slamm on it if ya want. It should be broken in by now. When I am done my rebuild. I am going to do this and post the results. I think this is as you all said a debated process its a whatever you want to do type of thing. If its gonna be driven hard then whata you do? Drive her hard the first 20-30 miles, drive it consevatively to last with manufacturers break it or haynes procedure. Either way they will seat one way is slower than the other. I'd say chme in here some one but this is one those deals where its "use at your own Risk" or "Pick you Poison"
 
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