I am considering the 12mm ARP's just wondering if they need a re torque? Any opinions are welcome.

 

Ok sounds good. I will contact you when I do the install for some tips.

 

12mm studs do not require retorque.

10mm studs do require retorque.

 

I'm sure John from EvoSpec will pop in here soon and enlighten us all

 

Search the forum its been talked about for awhile. What i posted above is correct.

 

word of advise ask around whos willing to stand behind their head sealing procedure under the provisions of if they lift the builder/person giving the advice covers the cost to reseal the heads. your list of people who will stand behind the choice of head studs your choosing to be a very short list if anyone.

this is one of the ways the porsche builders got thier customers back in the day 100 hours for a full engine build, plus 33 hours to tear down and retorque.

So choose your Poison wisely.

 

The ARP 12's should be fine. 12mm is pure brute force, it will hold. I will get the surfaces right and I will use a good torque procedure.

 

IMO its the not the stud that fails, its the studs seating/ threading into the case that fails. This is more important and getting a gradual increase of torque with heat cycles to keep the clamping pressure.

I hope it works out for you, your likely looking at purchasing the timing tools to do the retorque after your cycle it a few times.

if your building the bottom end yourself you should ask around at some of the specifics when building a boxer style engine.

 

I'm sending my cases to SRM early next week to be drilled and tapped. Sean will get it right. I will get some advise on building the engine. Actually it is pretty similar to some of the Japanese motorcycle engines I've built. You have to get everything straightened out on the cylinder stack and measure the squish and adjust with different thickness base gaskets. I will get it all measured and set up correctly. I'm pretty confident I can do it. I will probably take it somewhere to set the cams.

 

The 12mm has more threads and are thicker than the 10mm studs. Also the 10 mm studs use 60 ft/lbs max and the 12mm use 90 ft/lbs

 

Not what i was getting at never did i mention 10mm studs, im talking about the tolerance of the threads cut into the block versus the stud, then some use moly lube some dont, some studs seat to the bottom of the hole for preload some dont. Its all about getting the stud to not move once you install it.

The 12mm stud is not going to deform but the case can/will deform if they are not machined correctly is what i mean.

With SRM doing the machine work they should have that sorted out.

an example im going to give of the studs not holding is say you used a tap that the tolerance was not 100% perfect and maybe it was worn a bit cause you've used it before and it left a less then perfect cut on the case, then you put the stud in and its not as tight as it needs for our purpose. and even though you torqued it. the heat cycles allow it move ever so slightly.

 

That is impressive. I didn't know it was that much more.

 

Also, I'm going to do a mock engine build by putting my junk engine back together to establish procedures and check them as well as taking measurements. I don't know that cylinder measurements are available, so I will have to figure it out myself to replicate it on the new engine.

 

That seems like a good idea to test the quality of the studs before install. After they are tested and all check out, why would it matter how much the material in the aluminum threads, sleeves, gasket, and heads compressed as long as all of the nuts are torqued to spec? Would it only indicate that my parts are bad and need replacing?

 

I will do some research on angle torquing and I will see if I can use it to double check my install. I'll let you know what figures I come up with.