I just bought a set of ARP head bolts. According to their docs, you are supposed to cycle the bolts 5 times (tighten, loosen) They are 7/16-14 = 73ft/lbs with 30wt/oil as the lube.

On the first tightening I stepped from 30ft/lbs to 65ft/lbs; the bolts felt squishy, when I took them out the lengths were wildly different:
Like, one was 4.575, and another was 4.356; they started out the same length too...

I'm guessing the bolts are toast. Anyone have any experience dealing with ARP, or summit, which is where I sourced 'em? What should I say? Or are they going to tell me I'm screwed and have to buy $80 worth of bolts again?

 

Well, when you torque something it will stretch (that is what torque actually is about) But, I have never heard of ARP's bolts being "squishy", I used them on my heads and when they torqued they felt "crisp" when the torque wrench clicked at proper torque.

Try torquing them again and see if the lengths become more equal. The bolts should all end up about the same length (the ones that started the same) when torquing. If they don't then I'd suspect that something went wrong with their heat treating process. Give them a call and see what they say.

 

if you have over .2 increase in length then you should also have signs of deformation and proof of a defective bolt(s). contact ARP tech about it.

 

I've heard about this happening to ARP rod bolts before, stretching too much before they got to the torque rating, I know of a few racers that will take new ARP equipped rods and throw the ARP's away and replace them with Pioneer rod bolts, then resize the ends!!! Somebody correct me if I'm wrong here but as far as I know bolts are supposed to stretch a certain amount but they should return very close to the original dimension when loosened unless they were over torqued or unless they are the torque to yield type head bolts that are supposed to be used only once and then tossed, the bolts being .219 different would be WAY too much stretch. I would think either the bolts are too soft or your torque wrench is not calibrated correctly.

 

my arp head bolts tighten right down...

 

That depends on the bolt, application and amount of torque involved.

This is the first bad thing I have heard about ARP's bolts, would be sad if it has become commonplace.

 

Right, they are supposed to stretch, but they are also supposed to return to the same length or else they have exceeded their elastic limit. The ARP cataloge says:

If there is a permanent increase of .001" in length, or if there is deformation, the bolt should be replaced.

I guess I should call summit first and see if they can handle it? Sound like the thing to do, or should I call ARP first?

 

How do you know your torque wrench is accurate? Had it calibrated lately?

 

I don't know for sure, I didn't take it anywhere and have it tested, but I clamped the drive in a vise and hung 50 lbs 18" from the end. Figured that would be 75ft/lbs of torque. The wrench would click just barely when I had it set on 79. Maybe not the most accurate test, but shouldn't be bad?

 

mine too.

 

Has anyone tried the head studs? I might get a set when I do my head swap. Seems like that would make lining up the headgasket and head much easier.

Im definetly gonna get a set for my intake manifold next time its off. I think that would be much better.

 

i was gonna get studs but decided against it untill i have a reason...

i havent ever heard of ARP bolts strecthing..thats weird

 

ive never had any probs with my ARP bolts. my entire motor was held together with them, from headbolts to rod bolts to intake.

noone ive ever known has had any probs with them either...

 

Did you chase the threads first also? This should give a more even stretch with all your bolts. It you have a few holes with more drag, they would require more torque to get the same stretch as those with lower drag.

Ron

 

Any bolt or stud made of any metal will elongate when force is applied. Unless a fastener is made of diamond, it will distort under load. The key factor is the control of the amount of this elongation.

ARP is like nearly every other fastener manufacturer in the world. They don't make their own raw material, but purchase the wire in coils. Even the Japanese mills that make, anneal, and draw the wire have uncontrollable variation. They try to monitor heat lots for variation, but sometimes it gets out the docks anyway. Every company that heads bolts experiences some material variation and failures. Most companies use SPC and final testing to isolate lower quality batches of product. Most of them hold QS9000 or ISO9000 (or various of their iterations) certificates of quality process control. I've not seen either designation in ARP's advertising nor mention of it on their web site. I'm not sure if they have earned the certification, but it isn't apparent. They DO list the MS-21250 certification from the GAO, but that really has little relevance in fastner production, since it is only a group part number for federally specified bolts which have some minimu requirements under F.Q.A. More smoke and mirrors?

The point is, while ARP probably makes a fine product, they cannot magically make them better than any other fastener of the same material and process, and don't apparently have the minimum certification to sell to automarkers requiring ISO or QS standards (which is about 100% of them worldwide). Their bolts will stretch just like anyone else's, and most of us simply don't bother to do a QA assurance test on items we buy. Evidently, Spifz did that, and now understands the reality of the situation.

 

Call Summit before ARP. Summit shouldn't give you any problems.

 

Called Summit, explained, they told me no problem, call ARP and see if they have anything to say.

Called ARP, they said no problem, tell Summit that we recommend a full replacement and we will take care of it.

Called Summit, they overnighted me new bolts for tomorrow.

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