HELP! 22ft. lb. torque on head bolts?? Really?

Phx flyer · **Joined:** Fri May 27, 2016 10:57 pm **Posts:** 21

Your comments are appreciated. If what you are doing stands the test of time, it is sufficient. I am very familiar with arp products and have head studs made as well as rod bolts by one of the companies that also supplies studs/bolts to arp. For the future, and my own interest, I will be measuring the clamping force of various head bolts vs head studs for consistency.
The variation in clamping force with identical torque is of interest to me as I have measured considerable variations in the past with other fasteners. What would you expect the variations on an arp head stud clamping force to be with 130 ft lbs of torque? What variation is acceptable ? Also of interest will be the change in clamping force if the nut is loosened and then re torqued. In other race engine configurations, my interest is measuring oem clamping forces to know exactly what a head stud torque replicates the oem force. I also have custom head gaskets made to my specifications/ applications. I have not built a vm 2.8 and have one ready for a future build. I will not be using arps recommended torque , it will be by degrees rotation developed by actual measurement. If it proves that the studs I use have acceptable repeatability using a torque wrench I may choose to use it----if the studs/nuts come out of the same production run. Thread rolling dies change with use. Heat treat, micro finish on threads also varies.
If interested, find a copy of NASM 1312, a good read on fastener manufacturing quality issues that may be an interesting read . I find it quite educational.

geordi · **Posted:** Thu Jun 09, 2016 2:57 am

You should contact LMWatbullrun (his username here) as Larry knows far more about the esoteric information you are seeking than I will ever even contemplate.

I know enough to trust the research and the usage in this application, he was one of the ones that worked with ARP to develop this application.

connolcj · **Posted:** Thu Jun 09, 2016 8:25 am

geordi wrote:

I'm in the process of assembling that engine that I got from you Nick, and haven't even touched it yet - I'm waiting on the head gasket and rockers to arrive right now, and taking the time to wash down everything that I'm going to be putting on the engine. I just bought a parts washer today and it is filled with mineral spirits - seems to be doing a good job so far on cleaning some of the worst mess.

If I knew of a place that sold Kerosene at the pump, I'd probably try that too, as it is bound to be cheaper than the mineral spirits I got from Home Depot at $15/gallon. Ouch.

Anyway, I will be using a 2-hole gasket and the copper-kote on this one, no matter what. It will be sealed, period. Then of course the studs. Like we had talked about when looking at this one, I think that ridge at the center of the liner is the problem: If that impacts the bottom of the head, it *could* be an actual fire-ring kind of design... BUT there isn't a matching and deformable dent in the bottom of the head! So if those contact each other, then the gasket is not being compressed properly and you warp the head. The layers of the gasket are the only sealing surface, so I am inclined to believe thicker is better on the gasket.

The seal of the cylinder and holding the liner down is done by the wider flange of the liner outside that raised ridge, that is why the bottom of the head has a 3/8" wide fire ring mark on it, made of that coating that is on the gasket. You should probably scrape any old off of the head if it is there.

So this is interesting to me as I'm about to start the process of reassembling my engine that dropped a valve and took out the number 1 piston. I have it down to almost the bare block with the only exception being the 3 other original sleeves were left in. I'm planning on having the block cleaned and inspected along with a few other parts at a machine shop before I begin to reassemble it. My plan was to set the liner and shim it properly and get the right gasket to match my measurements. Should I just plan on getting a 2 hole gasket and just set the liner protrusion to the correct specs? I have been in contact with the VM Specialist in Europe to source a "new" head for the engine.

geordi · **Posted:** Thu Jun 09, 2016 3:30 pm

I would shim it so the liner is flush with the top of the deck or *maybe* just protruding a whisker, whichever the specification in the manual calls for. The flat flange is the sealing surface, so bear that in mind. I would think it needs to be just above the deck enough to be caught with a feeler gauge, and then yes, go with the 2 hole gasket for maximum squeeze and of course, studs. I would also use Copper-Kote on the deck and both sides of the gasket and the underside of the head, for maximum safety factor. A thin even coating is plenty, it goes on like spray paint. Wait until it is tacky, and assemble.

But that is just how I would proceed - Please note that I *have not* reviewed the directions / specifications in the service manual about this, but I *would definitely* suggest looking and comparing BOTH the 2005/2006 manuals for this because they frequently are not the same.

GordnadoCRD · **Posted:** Thu Sep 22, 2016 1:21 am

I am reassembling mine with ARP studs as well, but have taken a slightly different road, that hopefully will allow problem-free removal of the lower portion, should a stud break, and will help prevent thread creep when tightening.

Hercules 15615 is a thread sealant for geothermal pipe.

It will take a light set, which, when used on the ARP Stud-block thread, holds less than strong finger tight, yet will never harden, is unchanged to over 500 degrees F and against any fuel, solvent, lubricant, etc.

I installed the studs, and set the block-to-tip height to 4.25". Currently it sits waiting for parts to allow continued reassembly. When the parts arrive, next will be ARP thread lubricant for the washer, both sides, for the nut end threads, and torqueing. There is no need to worry about the studs being too high or low, since the Hercules will hold them from moving. Since it never hardens, if anything else happens, removal will be a snap.

geordi · **Posted:** Thu Sep 22, 2016 11:26 am

The point about the studs being too high or too low has EVERYTHING to do with proper thread engagement in the nut, and NOTHING to do with the possibility of "thread creep" since that is impossible.

Please do not start with the studs already in the block, that is not how the process has been developed from ARP.

Because the block threads are wide (steep ramp) and the nut threads are narrow (soft ramp) when you attempt to rotate the nut with the stud snug - it reaches "finger tight" instantly and the stud no longer moves while the nut rotates freely and torque ramps up smooth and slow.

The procedure to install the studs is to lube and preassemble the nut and washer onto the stud, with the top of the nut flush with the top of the stud - this is maximum engagement of the nut threads.

I have found that even when starting with a fresh head gasket, less than half of one revolution is gained by completely installing and torquing, and then removing one by one to re-set the nut to flush with the top of the stud and re-driving the stud to finger tight. The initial starting position of the stud (just as it touches the block threads before engaging them) is more than one stud-diameter away in length from the finger-tight depth. My understanding of fasteners is that once you have engaged more threads than the diameter of the fastener, no further strength is developed. So if the stud is "5 threads wide" and you can spin it 10 threads into the block or 11 threads... That will not make a statistical difference in the strength.

On the last two head gaskets I have replaced (with new valves and studs) - one was a re-used gasket and the other was new. Both were installed as I described here: Preassemble the nut and washer with plenty of lube onto the stud, and thread down to finger tight with the head.

I then torqued to 80 lbs according to the pattern, nuts 1-5... And checked the finger-tight of 6-10. They rotated less than 1/4 turn to finger tight again. Continue following the pattern through nut 18, everything to 80 lbs. Restart the pattern, now to 130 (for the re-used gasket) for nuts 1-10, and 120 lbs for nuts 11-18.

I added an intermediate stage of 100 lbs for the new head gasket, but the results were the same - the nuts all ended up with just about 1 thread above the nut visible, indicating that THEY had rotated just about 1 full revolution from zero torque to full - and that is precisely what happens when doing a one-by-one replacement on an already-installed head. So I do not see any difference in how the head gasket compresses (not much!) or any need to remove and reset/re-torque the studs during installation unless there is more than one thread protruding from the top of the nut. Yes, we want maximum block engagement, but I believe we are achieving that goal.

HELP! 22ft. lb. torque on head bolts?? Really?

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