Retightening head studs?

65Fastback

Active member
Hi,

I have slight oil sweat coming out all along the head gasket (only on the driver side) of my OZ250 head since I got the engine.
Is it wise only to retorque all head studs in the specified sequence with the specified end torque?
A ARP head stud kit is build in. I case yes, are the 70-75 ft-lbs from the shop manual the right torque even with OZ head an ARP studs?

Or needs the head to be removed to replace the gasket and check for flatness? The head was flattened some years ago when the engine was rebuild. In this case I would let it as it is.

Cheers
Joerg
 
Torquing using factory specs only works when using OEM factory bolts and fasteners. ARP, and most all aftermarket bolt and stud manufacturers have their own specs for torquing their bolts and studs because they are made from completely higher quality grades of steel than OEM bolts are made from. So your problem may lie from them being under-torqued instead of using the correct ARP specs. You'll need to search and verify the part number for the ARP fasteners being used and follow ARP's recommended torque and also use their special lube on the threads and under the heads of nuts and washers.
 
Howdy Joerg:

CNCs advice is solid. What head gasket did you uses? The stock specs are good for factory head bolts and with an OEM type steel shim head gasket. IF you're using FelPro head gasket, I've seen a list of compressed thickness at various torque values- from 70 psi to 100. Personally, I'd be a little concerned about the integrity of the stud holes at ratings over 85 psi.

Yes, it would be good to know what torque the ARP studs are rated. But, I would not hesitate to start by verifying the current torque of your head studs. Make sure that they are still at 70 psi. IF any are not bring them up to standard, wipe the seam clean and assess. If it still weeps, try a setting of 75 psi. Yes, use the correct order for re-torquing

NO, you do not need to change to a new head gasket to re-torque.

Good luck and keep us posted on your progress.

Adios, David
 
Thanks a bunch for these inputs!

The ARP manual says 80 ft.lbs as final torque. It also states that their fastener assembly lube must be used when torquing.
Does this mean that I need to loosen all nuts, clean them up, apply the ARP lube and then do the 3 step torque process?
Or just retorque the nuts as they are to 80 in the specified sequence?

David, psi and ft.lbs. are equal? I come from the metric part of the world ;-)
Regarding the head gasket I cannot say which was used. I see metal material at the edges.

Cheers
Joerg
 
Howdy Back Joerg:

Oops. Sorry, Yes, it should have been foot pounds of torque. Sometimes my brain leaves the station without me. Sorry for the error.

In this case, I don't think it matters much what gasket was used. How long ago was this engine put together? IF it was within the last ten years or so, it is most likely a composite type gasket.

Since you have ARP studs, I would do as follows. First, I'd check all stud nuts to determine what torque value they are currently holding. If they are not all even, start by evening them. That would establish a starting point. All nuts should be at the same torque rate. IF all nuts are at 70 ft. lbs. and you are still getting weep, try 75 ft/lbs. This is where a torque wrench with a dial read comes in handy as opposed to the clicker type torque wrench.

Since you didn't assemble this engine you will not know if lube was used on the studs, so at this point let that issue be. IF/when you have to remove this head, plan on using assemble lube.

Do you know if this head was milled in the rebuild process? How much? How much has this engine been run?

Again, Sorry for my mistake in terminology. Keep us informed on your progress.

Adios, David
 
Hi David,

now it is crystal clear how to proceed. Thanks alot. I will do this during the winter break.

The engine was completly rebuild with the OZ250 about 9 years ago but seldom driven by the previous owner. Thats why I was lucky to swap my stock 200 with him. The head was flattened but not milled in terms of compression increase (only sealed power flat top pistons for this). Not more than a few 1000 miles driven since then, I would say. A real great street engine, see specs below.

Cheers
Joerg


65 Mustang Fastback, 68 Inline 200, OZ 250 Head, Holley 2V 7448 350 cfm, Comp 260 cam, Hooker Headers, 2” dual exhaust, DSII, MSD 6A, 4 speed toploader, 3.2 rear end.
 
You guys mind if I tack onto this thread?

About to put an Aussie 2V250 on a D8 200 block. Looking for new ARP studs. All I can find specific to the 200 are these 2 variety at ClaySmith.

Does the cast iron 2V250 head require the standard studs or the presumably longer 250 CI Aluminum version?

http://www.claysmithcams.com/bolt-and-stud-kits/

Thanks in advance!
 
U could start a new thread & get better response...

"...All I can find..."
did U use our bud Matt? Try his site: vintage inlines dot com. U can use the PM function on his site, and he's gone 4 a wk or 2 (back April 11? - it's posted on the site). His prts cater to these motors & members here.
(y)
 
back 2 our German friend Joerg.
U state oily residue...sure it's not 'watery residue"?

As Comet sez there's leakage some folks see in the normal course of events.

Any steam shootin out? How much we talkin here? How long ya notice it?
Anything unusual on dipstick? Fill the radiator every few miles? or the oil?
 
My thoughts on arp vs stock or grade 8 bolts from the hardware or whatever is that torque is torque. The water gets muddy with the finish of the threads, oil used, washers and esp. the stretch to hold spec. Arp has specific stretch specs for their fasteners. Unless you can measure this stretch you should stick to the stock specs. Arp has specific guidelines for the bolt stretch on every particular fastener they sell and state it should be measured to achieve the best hold. I'm sure it wouldn't hurt to back them, any type, all off slightly and retorque them in sequence center out cold.
 
chad":2sbq2slo said:
back 2 our German friend Joerg.
U state oily residue...sure it's not 'watery residue"?

As Comet sez there's leakage some folks see in the normal course of events.

Any steam shootin out? How much we talkin here? How long ya notice it?
Anything unusual on dipstick? Fill the radiator every few miles? or the oil?

Hi Chad,

thanks for coming back to my topic. The residue feels, smells and tasts :D like oil.
I decided to life with it as it seems to be common to have small amounts of oil residue on the driver side.
I injected a small amount of motor silicon along the gap from the outside which helped somewhat.

Cheers
Joerg
 
I just got my car back today with the rebuilt engine. My guy used a thin bead of sealant on the drivers side to stop the oil weeping. We will see if it works.
 
water sepage, only, traditionally the problem (minute & liveable). NOW oil is added to the "expect it" on fresh motor?... hummm.

Back to OP, Joerg, the bruddha froma nother motha. Thanks for the tq spec post. I'm on ur schedule (Sept post, now 7 mo later the next). Mine has been on the stand so long I hadda pull the head. I saw (remote 'tv camera')the mice had left a kernal of corn in there frm the chicken feed, far side of the garage.
8^0
Forgot'n lost da tq spec 4 the APR studs (wuz gunna do 70#). Goddid right now w/ur help!
:beer:
Have a West en hitzen feltzer cramin lagen on me! (actually I like Anger wheat - any variety!) (y)

(how come the Brits'n Germans make such good beer? 700 yrs of experience?)
 
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