 |
924Board.org
Discussion Forum of 924.org
|
| View previous topic :: View next topic |
| Author |
Message |
WEASEL149
Joined: 19 Aug 2005
Posts: 595
Location: UK, Sheffield
|
 Posted: Mon Aug 12, 2013 2:52 am Post subject: |
 |
|
| Carrera RSR wrote: | | I have been highlighted that Steve Bassington would install with a light torque to ensure all studs are treated exactly the same. If this is the answer then at what torque should the studs be installed. |
Steve, this is where I read the information. Took me a while to find it again.
http://www.924board.org/viewtopic.php?t=17020&postdays=0&postorder=asc&highlight=head+gasket&start=75
"From memory there is no issue with the little had locating clips, unless yours is deformed slightly and wont let the stud throgh. Don't wind the nut on until you have bottomed the stud.
I have actually stopped using the rear locating clip. I now fit the stud into the block in the top left end, fit the gasket, use the front clp to locate it all. Then with the head swung up, slide it down the rear stud, then as it is close to the block, swing it down and locate it on the front clip. This means you are not juggling the head around trying tpo find the two clips to locate the head. Then drop in a couple of studs to hld the head, and you're set. All in all, much easier process. Of course, you need to have the inlet manifold removed et, but it is well worth it. Make dropping the head on a snap, as opposed to sliding it around to find the lugs, realising the gasket has dislodged and starting again
Smoothie, 85ft/lbs is 85 ft/lbs. You don't use lower torque values. As you say, the ARP studs have a fine pitch on the top thread. This allows a greater tensional force to be applied. It also allows the stud to stretch in a more controlled manner. But the clamping force is that which you apply via the top nut. And if you wind the ARP studs to 85, or the stock nuts to 85, you are still applying 85. The ARP studs can take significantly more than 85 though. Also, there torsional strength is much better, so the posibility of the head lifting under high boost/compression is greatly reduced. If you look at the torsional strength values of a stud vs a nut vs a bolt&nut, the stud is way ahead on strength. The advantage of these studs is that a more controlled clamping force can be applied, the studs stretch is a more quantified amount, so there is less likely hood of head lift, and as they are significantly stronger than the stock item, an additional 5/10ftlbs can be applied if required. But, all studs must be bottomed evenly to ensure equal loading. If one stud is only 2/3rds down into the block, this will put unequal strain on the bottom thread pitches of that stud and change it's stretch characteristics. So before you fit these studs, make sure you run a tap down the hole to clean the thread, and test fit each stud into a hole so that you can confirm that they all bottom equally. And use LOTS of the AP aasmbly lube. I would recommend buying an additional 4oz pot, to be on the safe side.
In this picture, you can see i have fitted the studs into the block, and am ready for tightening down. I even wound them down to an equal torque of 15ft/lbs with the integral allen socket and then measured each one for it's height off the deck. Then when i fit the head, i repeat this process, by torquing down the stud, and taking a measurement from the washer seat in the head to the top of the stud. Details, details, details. The devil is in the details. of course, this is only necessary if you are building a high HP motor, but it is best practice, so i would recommend it to all. And remember, NECER snatch or tug at the torque wrench to get the click. Use a steady, even pull to set the value. Repeat 2-3 times to be sure, but NEVER, EVER snatch or tug. And for these nuts, buy yourself a good quality 12 point socket. And use LOTS of lube!!!!"
_________________
1979 UK 932 |
|
| Back to top |
|
 |
WEASEL149
Joined: 19 Aug 2005
Posts: 595
Location: UK, Sheffield
|
| Posted: Mon Aug 12, 2013 3:37 am Post subject: |
|
|
With regards to nuts feeling/coming loose, it's most probably down to not achieving the correct clamping stretch of the stud itself.
The 90ft/lbs is a figure worked out to achieve ~75% of yield strength of the studs.
Along with the normal error you get when using a torque wrench, friction plays a big factor.
It's imperative that the stud holes in the block are clean (and free from oil as Ideola said).
You should be able to screw the studs in with your fingers until they bottom out on the shank with NO binding at all.
The stud holes should also be chamfered.
Clean all the threads on the ARP studs and you can check the other end by screwing the nuts all the way down the threads by hand - again NO binding at all.
Mating faces of nuts and washers should be nice and smooth - any adverse friction throws off your torque.
Next it's important how you go about tightening the nuts. ARP recommend only 2-3 stages and make sure the last final torque is a decent amount more than the last.
You'll read tons of BS on other forums about taking them down in a million stages of like 10ft/lbs at a time but all this does is give you an inaccurate torque setting.
I would make sure the last pull to 90 is at least 40ft/lbs (so from 50 to 90)
The reason for this is that static friction is greater than dynamic friction.
I intend to use a similar method to Bass GT. Torque the studs in the block to 15ft/lbs first of all.
Then after applying plenty of ARP lube to the stud threads and the nut mating surfaces, torque the nuts to 30ft/lbs. I'll then probably cycle them a few times to make sure they're equal before going for the final torque of 90ft/lbs in one steady pull.
You can then measure to your hearts content as Bass GT did.
Watch the Mittelmotor engine build vid Steve - you'll see that the guy doesn't mess about on the final pull.
IMHO I think all head fasteners should be checked after one heat cycle. You won't upset the seal, even if you check a number of times - but always make sure the engine has fully cooled down.
_________________
1979 UK 932 |
|
| Back to top |
|
|
Carrera RSR
Joined: 08 Jan 2010
Posts: 2312
Location: Somerset, UK
|
| Posted: Mon Aug 12, 2013 5:45 am Post subject: |
|
|
Thanks for this Wes.
Yesterday I cleaned out the bolt holes and plugged them to avoid any crap getting back in. I ran one stud in and it bottoms out before the waist at the top of the thread sits into the chamfer of the hole, is this OK? Should I take a millimetre off the bottom of the stud? The reason I ask is the stud was in hand tight but still had some lateral movement of the stud. I also read on a Cossie forum that the waist needs to hit the top of the hole and not bottom out.
I retorqued the nuts after 200 miles to 110Nm or 83ft/lbs. I read that the ARP studs are torqued to a lower than OEM but at 85 or 90ft/lbs then this is actually higher than OEM. Interestingly the Cossie engines also run 110Nms/83ft/lbs stock but their ARP instructions state 81ft/lbs. They also have to 'rest' the torque down sequence for at least 4 hours before the final torque phase
_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252 |
|
| Back to top |
|
|
WEASEL149
Joined: 19 Aug 2005
Posts: 595
Location: UK, Sheffield
|
| Posted: Tue Aug 13, 2013 1:14 am Post subject: |
|
|
| Carrera RSR wrote: | I ran one stud in and it bottoms out before the waist at the top of the thread sits into the chamfer of the hole, is this OK? Should I take a millimetre off the bottom of the stud? The reason I ask is the stud was in hand tight but still had some lateral movement of the stud. I also read on a Cossie forum that the waist needs to hit the top of the hole and not bottom out.
I retorqued the nuts after 200 miles to 110Nm or 83ft/lbs. I read that the ARP studs are torqued to a lower than OEM but at 85 or 90ft/lbs then this is actually higher than OEM. Interestingly the Cossie engines also run 110Nms/83ft/lbs stock but their ARP instructions state 81ft/lbs. They also have to 'rest' the torque down sequence for at least 4 hours before the final torque phase |
I'll have a look at this later in the week when I get over to my Father's place.
I had a read of some of the Cossie forums - they're a prime example of contradictory info.
I've never heard of the waist needing to hit the top of the hole but the lateral movement you mention is a bit of a worry. I will check my own in this respect to compare.
The torque values of 81ft/lbs and 83ft/lbs are wrong for the current kit with part number 251-4701.
The final torque should be 90ft/lbs. These studs have been revised over the years and have gradually gone from 186000psi to 190000 and then to what they are now 200000psi.
The higher the strength of the stud, the more torque it will take to stretch them to the correct preload. This may be part of your problem.
This is the link to the ARP PDF instructions for this kit:-
http://arpinstructions.com/instructions/251-4701.pdf
So following their method it will be 30, 60, then 90ft/lbs.
I also read somewhere else of a race engine builder torquing the studs into the block at 10ft/lbs so take your pick with that 
_________________
1979 UK 932 |
|
| Back to top |
|
|
WEASEL149
Joined: 19 Aug 2005
Posts: 595
Location: UK, Sheffield
|
| Posted: Tue Aug 13, 2013 1:38 am Post subject: |
|
|
| Carrera RSR wrote: | | I read that the ARP studs are torqued to a lower than OEM but at 85 or 90ft/lbs then this is actually higher than OEM. Interestingly the Cossie engines also run 110Nms/83ft/lbs stock but their ARP instructions state 81ft/lbs. They also have to 'rest' the torque down sequence for at least 4 hours before the final torque phase |
It's the Raceware head studs that are torqued lower than OEM bolts. These are what I've removed from my own engine and IIRC the final torque for those is 60ft/lbs.
This is what I find odd. If you go to the Raceware site they state the studs as being 205000psi rated, which is actually 5000psi higher than the ARP and yet they're torqued to a setting 30ft/lbs lower. That really doesn't make sense.
I could do with measuring the shank on the Raceware and also the lengths of them and compare to the ARP.
I have no idea if one is better than the other but at least ARP base their torque values on their own lube.
_________________
1979 UK 932 |
|
| Back to top |
|
|
Carrera RSR
Joined: 08 Jan 2010
Posts: 2312
Location: Somerset, UK
|
| Posted: Tue Aug 13, 2013 6:59 pm Post subject: |
|
|
| WEASEL149 wrote: | | Carrera RSR wrote: | I ran one stud in and it bottoms out before the waist at the top of the thread sits into the chamfer of the hole, is this OK? Should I take a millimetre off the bottom of the stud? The reason I ask is the stud was in hand tight but still had some lateral movement of the stud. I also read on a Cossie forum that the waist needs to hit the top of the hole and not bottom out.
I retorqued the nuts after 200 miles to 110Nm or 83ft/lbs. I read that the ARP studs are torqued to a lower than OEM but at 85 or 90ft/lbs then this is actually higher than OEM. Interestingly the Cossie engines also run 110Nms/83ft/lbs stock but their ARP instructions state 81ft/lbs. They also have to 'rest' the torque down sequence for at least 4 hours before the final torque phase |
The torque values of 81ft/lbs and 83ft/lbs are wrong for the current kit with part number 251-4701.
The final torque should be 90ft/lbs. These studs have been revised over the years and have gradually gone from 186000psi to 190000 and then to what they are now 200000psi.
The higher the strength of the stud, the more torque it will take to stretch them to the correct preload. This may be part of your problem.
So following their method it will be 30, 60, then 90ft/lbs.
I also read somewhere else of a race engine builder torquing the studs into the block at 10ft/lbs so take your pick with that |
I think I'm going to torque the studs at 15ftlbs and as instructed the nuts at 90ftlbs.
Annoyingly I asked the builder what proceedure to retorque and they stated as per OEM head gasket installation so I did what the Porsche manual stated, 83ftlbs. They never gave me back the ARP instruction sheet. I can safely say I shan't be using these guys again!
_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252 |
|
| Back to top |
|
|
Grenadiers
Joined: 20 Feb 2007
Posts: 3222
Location: Nelson, WI & Prescott, AZ
|
| Posted: Tue Aug 13, 2013 10:19 pm Post subject: |
|
|
I replaced my turbo with a rebuilt unit this past weekend. Since I've been following this post, I removed the valve cover for a peek. I too installed ARP head studs, and torqued them to 86 ft lb per Haynes I believe. After a track day, and a few hundred miles on the road, only one, the top middle one was loose, about 81 ft lb. At the track, temps and humidity were high, and was running laps close to red line. All is well with the Cometic!
_________________
'83 944 Track car.
'88 924S Track car.
'89 944 Turbo
2004 Winnebago Vectra monster RV
2012 Jeep Wrangler
2014 Kia Soul
2001 Ford F350 powerstroke |
|
| Back to top |
|
|
WEASEL149
Joined: 19 Aug 2005
Posts: 595
Location: UK, Sheffield
|
| Posted: Wed Aug 14, 2013 12:54 am Post subject: |
|
|
| Grenadiers wrote: | | I replaced my turbo with a rebuilt unit this past weekend. Since I've been following this post, I removed the valve cover for a peek. I too installed ARP head studs, and torqued them to 86 ft lb per Haynes I believe. After a track day, and a few hundred miles on the road, only one, the top middle one was loose, about 81 ft lb. At the track, temps and humidity were high, and was running laps close to red line. All is well with the Cometic! |
It's good to hear everything is well with your motor.
The torque values in the Haynes are for stock OEM bolts.
You should have received an instruction sheet with the ARP head studs and this clearly states 90ft/lbs in 3 equal stages with the ARP lube applied.
The reason for the higher torque is because the ARP studs have a higher tensile strength than the OEM bolts.
Looking at torque tables, 90ft/lbs isn't even 75% of the yield strength of the ARP studs, it's probably nearer to 112ft/lbs. I don't think it would be wise to take them down that tight though. The block threads could strip or stock OEM gasket could crush too much and deform.
I thought there would be more people chiming in on this subject. There are certainly people who frequent this forum with more knowledge than me. It would be nice to get someone else's experience?
_________________
1979 UK 932 |
|
| Back to top |
|
|
Joes924Racer
Joined: 03 Nov 2002
Posts: 11964
Location: Oregon, Denver Colorado native!
|
| Posted: Wed Aug 14, 2013 1:32 am Post subject: |
|
|
Your car looks happy. Very nice build by the way.
_________________
1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo. |
|
| Back to top |
|
|
Brockoli
Joined: 06 Feb 2007
Posts: 621
Location: Edmonton, Alberta, Canada
|
| Posted: Wed Aug 14, 2013 7:11 am Post subject: |
|
|
I also used the ARP head studs. After putting my head on I talked to another engineer at work about the torque since I thought it might be too high at the recommended ARP torque values (I thought it was higher than 90 ftlbs???). He mentioned that the cast iron block would probably be the limiting factor and was surprised that I didnt strip the block threads with that much torque.
_________________
'80 924 M471,Wideband O2, Full coilover susp,23/19 sways,Bilstiens,KLA Strut Brace,Roll Bar,Test Pipe,BBS RS, Willwood BBK
25% of a '87 944 Chumpcar http://straightpipe.ca/forums/showthread.php?t=2454
'79 924 Sebring Edition(Sitting) |
|
| Back to top |
|
|
Rasta Monsta
Joined: 12 Jul 2006
Posts: 11732
Location: PacNW
|
| Posted: Wed Aug 14, 2013 8:37 am Post subject: |
|
|
TSB on head bolt torque:
_________________
Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
|
|
| Back to top |
|
|
Rasta Monsta
Joined: 12 Jul 2006
Posts: 11732
Location: PacNW
|
| Posted: Wed Aug 14, 2013 8:38 am Post subject: |
|
|
Oh, and how do you like those heart-stopping pops as you stretch those ARP studs!
_________________
Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
|
|
| Back to top |
|
|
Carrera RSR
Joined: 08 Jan 2010
Posts: 2312
Location: Somerset, UK
|
| Posted: Wed Aug 14, 2013 10:54 pm Post subject: |
|
|
How many times can you recycle these ARP studs?
_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252 |
|
| Back to top |
|
|
CorsePerVita
Joined: 25 Jul 2008
Posts: 1992
Location: Redmond, Oregon
|
| Posted: Wed Aug 14, 2013 11:17 pm Post subject: |
|
|
| Rasta Monsta wrote: | Oh, and how do you like those heart-stopping pops as you stretch those ARP studs!
|
Pops? What pops?
_________________
- 1977 Porsche 924 2.0 N/A (Trackday Project)
- 1979 Porsche 924 2.0 N/A (The other daily)
- 1980 Porsche 931 (Daily)
- 1987 Lamborghini Jalpa
- 1999 Ducati 900SS |
|
| Back to top |
|
|
fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
|
| Posted: Wed Aug 14, 2013 11:55 pm Post subject: |
|
|
The nuts pop due to friction as they get tighter.
_________________
Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
924 FAQ (Technical)
