Arp 6-bolt Head Studs

[The Flash]

I was wondering if ARP 6-bolt head studs are reusable. I'm asking this because I was a
slacker when I replaced my block and never checked the head for flatness. Now after
1200 miles I have a blown headgasket.

 

[project_tsi]

Check them for stretch and if they check out, yes you can re use them.

 

[The Flash]

Thanks for your reply! I'm a little new to engine building, so could you explain to me how to check for stretch? Do I just look at them? Or do I need to get the specs and measure their lengths? If I do need the specs, would you know what they are? Any and all help is appreciated! Thanks!

 

[dsm-onster]

I certainly hope 6-bolt ARP head studs are reusable as I've had my head off half a dozen times since their original install... I don't think you should even bother with checking the stretch, IMHO. I never did. But you are having problems, and project_tsi knows substancially more than I . If you can't get the specs on their proper length, try eliminating other possible problems.

1. Did you loosen and retorque the studs in sequence after 5 heat cycles?

2. did you use moly lube or oil to torque them down? To what number did you torque them?

3. Why was the head off before the ARP stud install? Did you pop a HG then? Have you run a compression test and are you sure it is a HG failure?

 

[99redgst]

Thanks for your reply! I'm a little new to engine building, so could you explain to me how to check for stretch? Do I just look at them? Or do I need to get the specs and measure their lengths? If I do need the specs, would you know what they are? Any and all help is appreciated! Thanks!

Checking for stretch is a simple process. All you need is a straight edge and the stud. Set the straight edge against the length of the bolt, look at the threads if they all make contact with the straight edge its fine. If you notice that some of the threads are not touching and others are the stud is stretched and needs to be replaced. Usually the center of the threads is where you will see a problem, they would be shaped like an hour glass. The center of the treads would have a smaller diameter than the rest. Hope this helps.

 

[TSIfreek]

Checking for stretch is a simple process. All you need is a straight edge and the stud. Set the straight edge against the length of the bolt, look at the threads if they all make contact with the straight edge its fine. If you notice that some of the threads are not touching and others are the stud is stretched and needs to be replaced. Usually the center of the threads is where you will see a problem, they would be shaped like an hour glass. The center of the treads would have a smaller diameter than the rest. Hope this helps.

You check any bolt for stretch with a micrometer. Call up ARP and ask what the useable limit is . I highly dought they are stretched I wouldnt worry about it.

 

[diambo4life]

You check any bolt for stretch with a micrometer. Call up ARP and ask what the useable limit is . I highly dought they are stretched I wouldnt worry about it.

Agreed. I have reused mine ~5-6x now. However, I will be tossing a new set in when I pull the head next month.

I'm pretty sure there's a sheet that comes in the package telling you what stretch limit is etc.

 

[dsm-onster]

However, I will be tossing a new set in when I pull the head next month.

Have you checked yours for stretch? What were the results?

 

[99redgst]

Agreed. I have reused mine ~5-6x now. However, I will be tossing a new set in when I pull the head next month.

I'm pretty sure there's a sheet that comes in the package telling you what stretch limit is etc.

The technique I posted is the way Chrysler reccomends in thier service manuals. However I will agree that if there is a spec given the micrometer would be the more accurate. However most DSMers probably don't have a set of micrometers, well most probably don't have a precision straight edge either. However they can probably find something that will work sitting around the house. Here is a pic of what to look for, taken from a Chrysler service manual. Obviously taken to the extreme for illustration purposes but gives you an idea.

 

[huafist]

The technique I posted is the way Chrysler reccomends in thier service manuals. However I will agree that if there is a spec given the micrometer would be the more accurate. However most DSMers probably don't have a set of micrometers, well most probably don't have a precision straight edge either. However they can probably find something that will work sitting around the house. Here is a pic of what to look for, taken from a Chrysler service manual. Obviously taken to the extreme for illustration purposes but gives you an idea.

If you don't have a micrometer then you don't need to have an engine torn down in the first place. You have to have the proper tools for a job or you'll be doing it again.

 

[The Flash]

Thanks for all the input guys! It's very helpful. The head gasket failed because of a junkyard head that I installed. Since then, I have purchased a straight-edge that I will be using before I install my new head to be absolutely sure the block and head surfaces are within spec.. The car was pushing coolant on the dyno so I decided to do a compression test, and subsequently, a cylinder leak-down test to see how bad the gasket really was. The compression was 100, 90, 90, 100. At first I thought my new short-block was ruined. I immediately grabbed the cylinder leak-down tester. When I pressurized one of the cylinders with the coolant cap off, I got covered in coolant. This is how I came to the conclusion that the head gasket was blown.

I checked ARP's website and they stated that if a fastener is stretched more than .001", it should not be reused. I would use one of my micrometers to check them but I don't have one that big.

I really don't see why you need a micrometer to replace a head gasket because you usually just replace the head studs. What else would need a micrometer for when replacing a head gasket?

I may end up just replacing the studs so that nothing is left to chance. I will be using one of those SCE O-ringed copper head gaskets. I'll let you guys know how it hold up.

 

[huafist]

I checked ARP's website and they stated that if a fastener is stretched more than .001", it should not be reused. I would use one of my micrometers to check them but I don't have one that big.

Are you sure they mean .001" in length, or .001" in thread diameter variance?

I really don't see why you need a micrometer to replace a head gasket because you usually just replace the head studs. What else would need a micrometer for when replacing a head gasket?

You don't if you're replacing everything that could possibly be out of spec. However, putting things back together without checking things properly is asking for trouble. IMHO, anyone working inside an engine needs a basic set of automotive tools, including (but not limited to) 3 different torque wrenches, torge angle meter, micrometers, precision straightedge, feeler gauges, bore gauge, etc.
Having the proper tools ensures you have the ability to do the job right the first time (and thus, not have to do it again), and gives you the peace of mind of knowing everything is correct.

I may end up just replacing the studs so that nothing is left to chance. I will be using one of those SCE O-ringed copper head gaskets. I'll let you guys know how it hold up.

If I didn't have the means to check the studs, I'd probably replace them. However, if they're relatively new studs, it might be worth taking them to a local machine shop to have them checked. Most shops won't charge much to do something like that.
Good luck.

 

[Mark90gst]

use a mic, everything has to be perfect when your on the quest to make high hp, like me haha,

but in all reality they shouldnt strecth

 

[Suparata]

How in the world can you check for stretch if you have no idea where they started before they were used?

 

[1qkfwd]

Thanks for all the input guys! It's very helpful. The head gasket failed because of a junkyard head that I installed. Since then, I have purchased a straight-edge that I will be using before I install my new head to be absolutely sure the block and head surfaces are within spec.. The car was pushing coolant on the dyno so I decided to do a compression test, and subsequently, a cylinder leak-down test to see how bad the gasket really was. The compression was 100, 90, 90, 100. At first I thought my new short-block was ruined. I immediately grabbed the cylinder leak-down tester. When I pressurized one of the cylinders with the coolant cap off, I got covered in coolant. This is how I came to the conclusion that the head gasket was blown.

I checked ARP's website and they stated that if a fastener is stretched more than .001", it should not be reused. I would use one of my micrometers to check them but I don't have one that big.

I really don't see why you need a micrometer to replace a head gasket because you usually just replace the head studs. What else would need a micrometer for when replacing a head gasket?

I may end up just replacing the studs so that nothing is left to chance. I will be using one of those SCE O-ringed copper head gaskets. I'll let you guys know how it hold up.

I know this thread is very old but form experiance of torquing down mitsubishi heads, When doing you final torque after doing your three stages go over all ten studs again to make sure the head properly seated to the block. I have had two occations where I went over the three torque stages and and didn't do the final torque twice and the middle ARP studs where loose which caused the head gasket to blow between 2 and 3 cylinder. It shouldn't be a stretch issue with the ARP studs Im on the fifth time of reusing the studs and I asked the machine shop guy to check them. He told me no need to replace them unless there was total engine failure causing damage to the stud itself. Hope this helps new readers.