ARP head studs

LMWatBullRun · **Posted:** Thu Dec 06, 2012 8:09 am

It probably would be relatively easy to make a fixture to test these TTY bolts, but I suspect that the explanation for the tight removal on some is more basic- the oil used to lube the bolt head probably squished out the residual film over time and left the steel bolt in contact with the AL head. ( I did use PB blaster on all the head bolts; some I think it helped and others not.) Some micro-galling when removal was attempted probably ensued. I recall that when I got the tough ones to move there was an initial yield and slight movement of the wrench, maybe an inch or less at the end of the cheater, followed by increasing resistance, then a second yield that allowed the bolt to loosen. There was surprising variability in the amount of turning required to release the bolt; some were less than half a turn while others were 3/4 to almost a full turn.

Also, the oil used to lube the block threads was still in evidence when I took those out, and I never saw any evidence of gasket failure (Coolant or excess engine oil on the lower bolt threads.) I carefully inspected each one as I removed it. So my guess is that the problems taking them out had to do with the head to bolt friction. It may be that blowing all the lube oil off the bolt recess and using Kroil might make this easier; I will try that when I take the core engine apart to rebuild it.

If I were to test the yield of the bolt, I would probably make a fixture that allowed friction free rotation of the head of the bolt, something like a big tapered roller bearing for my Dodge, and I probably would lap the 12 x 1.75 threads

geordi · **Posted:** Thu Dec 06, 2012 11:54 am

The friction with the head is a distinct possibility, as is the degradation of the factory installation oil (if there was any to speak of). The environment that the threads exist in, is probably more than hot enough to cook off a light machine oil like the fresh bolts were coated with. The directions claimed that the bolts were already treated, and further oiling should not be done before installation.

As I installed those fresh bolts into the dead engine according to the factory book process (plus a bit extra turn on each for safety)... I would suspect that they will remove relatively easily. Both because of the oil still being there (only ~5 minutes idling) and because they hadn't ever experienced a real heat cycle. You could try re-using those or destructively testing them... But I think the strength of the head flutes is actually the weakest point on these, more so than the 'yield point' of the shaft. If there is one.

What I do suspect is that the variability in the installation torque and the 'turn it this many degrees' nonsense is because the iron block isn't machined with any clean tolerances in those holes. As such, I suspect that Chrysler knew this, and either the bolts don't ever get to their plastic-range yield spec and simply remain in the elastic range (Perfectly acceptable and preferable to my thinking)... OR they are planning that the initial installation and number-of-turns puts it *close* to the yield point, and the engine's flexing will finish the job.

No matter what, I still say one thing: TTY bolts suck, and I thank you for trying the studs for any of the members that want something better.

LMWatBullRun · **Posted:** Thu Dec 06, 2012 4:41 pm

I completely agree that TTY head bolts are suboptimal in many respects. They are cheap, however.

I also agree that the bolt head is more likely to fail than the shaft in torque, at least while the bolt head bears on relatively soft aluminum. However, I do not think that the variations we have seen are the result of poor machining of the block. The reason is that while I felt significant variation in unbolting torque, there was little variation in the force required to bring the clearance tap to the bottom of the block hole. Moreover, there was little perceived difference in the force required to seat the studs.

With all of that in mind, I think the most likely cause is tolerance stacking, poor installation, and the resultant stochastic variation in clamping force as previously discussed. ARP has a great graph that shows the differences between stock TTY bolts and studs in clamping force predictability.

LMWatBullRun · **Posted:** Sat Dec 08, 2012 6:30 pm

As stated above, I took some of the stud nuts off to see what they looked like.
Here is one-

MUCH flatter now! :lol:

You can see where the ridge was, you can see the scratches from the dental pick I used to check the area out, and you can see the 'aluminum foil' where the head deformed locally and delaminated locally when I crushed it with the stud/washer/nut.

In hindsight, it would have been much better to have removed that ridge before using the ARP studs.
That deformation can be a problem depending on what is near the hole. One of my lifter holes needed some minor lapping to restore free movement.

user113 · **Posted:** Fri Dec 14, 2012 12:43 am

Sweet. And you did this in a tent?

LMWatBullRun · **Posted:** Fri Dec 14, 2012 1:15 pm

user113 wrote:

Sweet. And you did this in a tent?

Yup. Don't have a garage built yet. Been busy with other things.

R2.0 · **Posted:** Thu Dec 27, 2012 4:57 pm

BTW, counterbores are available on McMaster Carr - 15/32" pilot x 7/8" body is about as close as you are going to get for stock tools. A little over $50.

LMWatBullRun · **Posted:** Thu Dec 27, 2012 5:01 pm

R2.0 wrote:

BTW, counterbores are available on McMaster Carr - 15/32" pilot x 7/8" body is about as close as you are going to get for stock tools. A little over $50.

PN, please sir?

R2.0 · **Posted:** Thu Dec 27, 2012 5:04 pm

LMWatBullRun wrote:

R2.0 wrote:

BTW, counterbores are available on McMaster Carr - 15/32" pilot x 7/8" body is about as close as you are going to get for stock tools. A little over $50.

PN, please sir?

3103A66
Changeable Counterbore Pilot 3/16" Shank Diameter, 15/32" Pilot Diameter
$7.22

3102A33
High-Speed Steel Changeable Pilot Counterbore 7/8" Body Dia, 1/4" Shank Dia, 3-1/8" Overall Length
$46.59

LMWatBullRun · **Posted:** Thu Dec 27, 2012 5:46 pm

Excellent.

I will include that information in the tech writeup. Thanks!

LMWatBullRun · **Posted:** Thu Jan 03, 2013 9:28 am

Several people have emailed me regarding the ARP stud Tech write-up I am planning, and I apologize for not having done it yet. With luck, I will have time this weekend, but won't promise that. The tech information RacerTracer got from VM Motori is on page 3 IIRC, and the photoessay on stud install is on page 5. R2.0 supplied the data for the face reamer needed to smooth a used head.

Spiegelmann · **Posted:** Thu Jan 10, 2013 10:26 am

Hello, i`m a newby owner of KJ 2007 2.8 CRD, from Russia Moscow, was looking google info about arp studs fo KJ 2.8 and went trough this topic, and have no clue what type of studs was used by LMWatBullRun, can anybody show me right kit partnumber?

racertracer wrote:

OK, I was able to get the info from VM Motori and I forwarded it to ARP and the following is the response I received.

"The part number of the closest stud that we have on hand is AU5.400-2LUB. The nut is AUN12-1 and the washer is AUW875N. Acceptable torque with ARP Ultra Torque would be about 100 ft-lbs.

Approximate cost is $15.00 for a set of the stud, nut and washer.

Best Regards,

Justin Phillips

Specialty Products Coordinator

ARP Inc.

1760 E. Lemonwood Dr.

Santa Paula, Ca 93060

(805)525-1497

(805)525-1441 Fax

justinp@arpfasteners.com"

and

geordi wrote:

OK - talked to ARP today, this is a link to the kit at Summit:

http://www.summitracing.com/parts/ARP-204-4706/

The ARP part number is 204-4706, but you need to buy two of these kits - ouch. That comes up to a LOT of cash. I'm about to call ARP and see exactly how much these would cost per piece, b/c my math says it would be about $100 cheaper to buy direct.

Annnd.... No it isn't. OUCH these things are expensive. $16 and change just for the stud, $4.50 for the nut, $1.03 for the washer. It is actually cheaper by about $25 to buy from Summit, but I have a decision to make now - if I can't order the gasket without the bolts, do I even care enough to spend ANOTHER $380 on this thing?

so what info is correct? and what is more compatible with original, hope for reple and sorry for my english, it`s not perfect. Thank you.

LMWatBullRun · **Posted:** Thu Jan 10, 2013 1:55 pm

Both the part numbers and the kit number are correct.

If you shop around, you can get 2 kits for $350 or less, and the kits come with ARP lube.
Keep in mind that 18 studs are needed, and the listed kit has 10 each.

BTW your English is good, I understood you perfectly.

Spiegelmann · **Posted:** Thu Jan 10, 2013 3:27 pm

Thank you very much, all you did good job for research, it helps me very much, as I'm look forward for my kj to increase power as soon as im finish my rover car project. Also to be grateful to you all if any of you need any technical support or technical data of yours cars I'm able to Chrysler dealerconnect so pm me if you will need sometime any help i can to do. Cheers

LMWatBullRun · **Posted:** Sun Jan 13, 2013 3:56 pm

I am pleased to announce that I was finally able to get back to the reassembly and put enough of this thing back together to check it. It runs. Actually, I think it runs more smoothly than it did when I took it apart, but it does run. Now in process of sucking the air out of the head to reduce the probability of air lock/overheat.

Will advise further developments.

racertracer · **Posted:** Sun Jan 13, 2013 5:41 pm

Congratulations, phenomenal work and a thank you for the documentation.

LMWatBullRun · **Posted:** Sun Jan 13, 2013 7:31 pm

Ran it for about 6 miles around the neighborhood, and all seems well. Will take it for a longer run later this week.

LMWatBullRun · **Posted:** Wed Feb 27, 2013 2:01 pm

Now have about 2000 miles on it and some relatively cold starts. The 7v glow plugs work fine if you cycle the key 3 times even at 10 degrees. I am no longer using any coolant, knock wood; do not know if that was the new WP or the studs but suspect that the studs flattened out an incipient warped head.

Now on to rebuild a transmission.....then to get a manual shoehorned into this buggy.

racertracer · **Posted:** Wed Feb 27, 2013 3:10 pm

LMW.

If you haven't already done so.... I would take it out for a long test drive on a long highway and see how it performs.

As with me, at first, the low coolant light would show up on the dash after a long hot drive. On a trip that was more than 250 highway miles.

And as time went on the leak gradually increased.

If you have not driven it on a long hot highway drive, then it may be a good idea to do so and eliminate any worries.

LMWatBullRun · **Posted:** Thu Feb 28, 2013 2:34 pm

It will be a few months before I get any really long hot drives, but I was losing coolant on 20 to 40 mile commutes. Now I am not. Cardboard/newspaper did not show any drips. Was this the WP or the HG? Who knows? I do know that I found significant variance in 'TTY' head bolt removal torque, and significant variation in rotation required to bring the ARP nuts to the required torque. Both of these facts are strongly indicative of a warped head, but I did not gage the head to confirm it.

Bottom line, studs ensure clamping force. I will be building the next motor with them.

ARP head studs

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