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TR2/3/3A TR2 head studs

Lockheed-driver

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Hello All. I’m looking for some advice regarding head studs…
I recently took the head off my engine to get new valve guides and valves installed. The head and block haven’t been separated for at least 40 years and because the old head studs were a swine to get out I decided to buy a new set of 10.
I was torquing up the head bolts in the correct order and in increments of 25 ft/lbs with a plan to reach 100ft/lbs as per the workshop manual. I didn’t get that far. All ten had achieved 50ft/lbs and I started torquing up no1 stud .. when it sheared. I estimate it failed around 60 ish ft/lbs. A guess… more than 50 and not 75.
Head removed. Broken stud removed after some gentle persuasion… phew!! All other studs removed.
The stud looks like it failed where the thread channel stops. Anyway … spoken to Uk supplier and I’m returning all studs as I now have now faith in this particular batch.
Having spoken to a local engine builder .. he said the older studs were probably of better quality of metal and why not use again.
What are your thoughts wise ones? Use the old? Are there any uk suppliers who sell studs of updated metal?
Anyone else had a silimar situation?
All advice gratefully received.
 
I am trying to get my tr2 on the road also, so glad to hear they are still out there. I have never bought new studs and rebuild a handful of these engines. When you put the engine studs in the block, either old or new studs, put them in hand tight or there is a possibility of cracking the block. Evidently the tongue can compound and make the final torque above a 100lb and do damage.

steve
 
My recommendation: Just bite the bullet and get the ARP studs. Shop around a bit, and you can find them at a price not much greater than the standard ones.

When you do the math, you discover that that 100 ft lbs of torque is about the limit of a grade-8 fastener.
 
The old studs are fine. There is a lot of superstition on this issue because people don't understand that stretched studs go back to their original length when the nut is removed unless they have been seriously over torqued. Google modulus of elasticity.
Bob
 
I am trying to get my tr2 on the road also, so glad to hear they are still out there. I have never bought new studs and rebuild a handful of these engines. When you put the engine studs in the block, either old or new studs, put them in hand tight or there is a possibility of cracking the block. Evidently the tongue can compound and make the final torque above a 100lb and do damage.

steve
Hi Steve Not sure what you mean by "the tongue can compound"? Karl
 
I thought the idea of compounding torques was wrong also Bob. However, when Mad Max and others on the forum were talking about how torques would compound if the studs where also torque at 100 lb. I just said ok. I guess it could happen, but really I do not see how either. Anyways, because of those old conversations on the forum, I now just snug the studs just past finger tight.

Steve
 
The old studs are fine. There is a lot of superstition on this issue because people don't understand that stretched studs go back to their original length when the nut is removed unless they have been seriously over torqued. Google modulus of elasticity.
Bob
Having a PhD in an engineering field, and over 50 years of experience, I think I know what Young's modulus is. It applies only within the elastic limit of the material, and when you approach the yield strength of the metal, you're outside that limit, and it is no longer that simple. At 100 lb ft of torque, the stress in the threaded part is around 90,000 PSI, which is probably comfortably below the yield strength of the stud, but only if you assume it is a cylinder, which it isn't. In reality there is nonuniform stress around the threads, which can create fatigue damage and be a starting point for a fracture. The older the stud, and the more beat up it is, the more likely this will occur. Note that studs invariably break in the threaded portion.

In my opinion, cylinder-head studs should always be replaced when an engine is rebuilt. Since we don't know the specifications of the studs from the usual suppliers, or whether the manufacturer really met that standard, I think that using ARP parts, which are high-quality and well documented, is a good idea.
 
Steve,
I think we got to this point in a years ago thread. We will continue to disagree about the use of used studs. In several years as a BMC line mechanic and in hobby work on Triumph, Jeep, Chevrolet, and Toyota, I have never prophylactically replaced a head bolt or stud. And have had no problem.
Bob
 
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Use original studs in good shape or new ARP and you won't have any problems. Anything else is a guess. If you do re-use any studs, be sure to thread a nut all the way down the threads. It should spin freely to the end of the threads. If it starts to bind, then the stud was stretched and it is junk.
 
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