How to check for broken head studs while the valvecovers are off?

[aigel]

Just took the valve covers off for the SC's first valve adjustment. No head studs or nuts came flying my way which is good news! I tried to feel the head nuts through the openings in the cam housing but can't reach them.

Can I inspect the lower head studs visually with a mirror or how is this done? E.g. in a PPI?

TIA, George

[Early_S_Man]

George,

Use a 10 mm, 3/8" drive hex drive bit and a 4" - 6" extension on a 3/8" torque wrench ... on all twelve barrel nuts for the bottom-row studs . Test at 24 lb-ft setting.

[aigel]

Thanks, S-man. What's the factory spec on torque? I mean, if they are toast, I will break them 'loose' much before 24 ft-lb. I am a chicken. Can I go 10 ft-lb and fell that I 'checked' them?

Off to get the 10mm hex drive bit ...

George

[Wil Ferch]

I would just put a wrench on them and be happy they don't fall off...I would resist putting any meaningful torque on them...especially the Dilavar row ...the steel row would be OK.. IMO.

---Wil Ferch

[aigel]

Wil:

That's what I am thinking. Why twist them if you do not have to. I will get the tool and loosely put it on there without a ratchet and turn it by hand to make sure nothing is loose.

Keep your fingers crossed for me. The engine is super clean for a 150k unit and performs flawlessly. I do not expect any bad news, but mightaswell check. If you drive around with broken studs, you really can rack up a bill for head work etc. If you catch it early and resist other upgrades, it is only labor and a few hundred bucks to fix it. .

Cheers, George

[vash]

if you are trying to avoid buying any more tools, you can borrow some stuff from me. but i think a 10mm allen socket is pretty "bread and butter" on these cars.
cliff

[Randy Webb]

"Why twist them if you do not have to."

- I fthey have loosened -- even imperceptibly, the strength is compromised ('cuz they can then flex with reciprocating loads). Bolts in tension are always strongest at their torque spec. "Twisting" them puts the right amt. of tension on them.

[Wil Ferch]

I doubt they loosen...they are installed with a Loctite sealer from the factory. I guess it *could* happen, but then there wouldn't be any real torque to start them to spin.

OTOH...put some torque on an otherwise good dilavar stud....hear it snap...and *then* say....Oh-Oh !

--Wil Ferch

[aigel]

As far as I am concerned, the decision is made. Stick the socket in there with an extension and carefully move it with my fingers, wihtout a ratchet attached. If the stud is broken, you will be able to tell.

Cliff, I may get back to you on the tool offer for if I need something more exotic than a 10mm allen socket. As you say, of course I need that as a permanent tool with this car.

Cheers, George

[caliber60]

One thing I learned while removing valve cover, don't use the power tool, use hand torque only. The power tool remove the nut with the bolt all together.

[Randy Webb]

Wil, If the proper torque caused a stud to snap, then it was bad anyway and you saved yourself the problem of it snapping while the engine was running.

For those interested in fasteners, a good source is Carrol Shelby's book - better than the hp one.

[Early_S_Man]

My point, exactly, Randy ... about testing the studs at full torque!

Don't you mean Carrol Smith??? Worked for Shelby on the GT-40 race team effort in the '60s!

[ChrisBennet]

I can see "retorquing them" after a recent rebuild but otherwise you are not duplicating the factory torque specs. The factory torque specs are for an antisiezed barrel nut on a clean washer - not on a nut that has been rusting to the washer and stud for over 20 years. I'd give them a little twist to see if they are more than finger tight but otherwise I'd let sleeping dogs lie.

I use a 10mm hex drive on a "wobble" extension to get to those nuts. It isn't a straight shot.

Caliber60: The valve cover studs tend to come out no matter what you do. I wouldn't swear off the power tools for that reason.

-Chris

[Wil Ferch]

Randy:
I've heard reports of mechanics just finishing up on a rebuild..and as they close up shop....they hear....for no apparent reason..."sproing"..and a missle comes shooting over their head. Yep...a broken ( all by *itself*) Dilivar stud. Like Chris says...let sleeping dogs lie. Simply put a wrench on the nut and see if its basically tight...or if it's basically loose. Wouldn't torque a "tight" nut and risk trouble...

..but that's me.

---Wil Ferch

[Randy Webb]

Sorry, I conflated the man with his team sponsor -- I did mean Carrol Smith, who worked for Shelby on the GT-40 race team effort in the '60s.

Wil, Chris - Yes, if the nuts are all rusted onto the studs then leave them alone. You guys are very naughty to let them get all rusted that way though....

If a good, lubed fit from nut to stud is (OK ignore the porno sounding aspects of this post) present, I stick by my original claim.

But hey - it's your car!

[ChrisBennet]

Originally posted by Randy Webb
Wil, Chris - Yes, if the nuts are all rusted onto the studs then leave them alone. You guys are very naughty to let them get all rusted that way though....

One of the downsides of having a leak free motor is that these studs don't get the "rust preventative coating" that would prevent that sort of thing.

I suspect that climate may shape how one feels about this. The studs I see here in the New Hampshire tend to have rust on the surface in places and the nuts have some corrosion. When I remove the heads I tip the motor up on its side and fill the inside of the barrel nuts with some PB Blaster and let them soak a while. When I go to remove them they make a "ping" sound as they break free. I haven't tried this with a torque wrench so I don't know if the torque to overcome the corrosion is higher than the torque spec.
-Chris

[aigel]

Just wanted to say THANKS again and give an update on the progress.

Checked all lower studs today by inserting the 10mm tool (bought a whole set!) with an extension and a ratchet attached. I just checked that they were snug, with slight writst torque probably less than 3Nm.

All studs are in good shape! I am very happy! Now I finally did my PPI. (Post purchase inspection in this case ...) and am ready for DE and AX!

Car is back together with a new left cam oil line (dist. had to come out) and a tuneup. Runs great, without tick from the freshly adjusted valvetrain!

Cheers, George

[Wayne 962]

Originally posted by Randy Webb
Wil, If the proper torque caused a stud to snap, then it was bad anyway and you saved yourself the problem of it snapping while the engine was running.

Sorry, but this is not good advice! The factory specs for these head studs are specified for a fully lubricated nut and washer. Surely by the time that you retorque them, the lubrication is gone, and you will be over tightening them - potentially breaking them. It is for this reason that Bruce Anderson told me he doesn't recommend retightening the head studs after 1000 miles of a rebuild - he says that you can't achieve a proper torque.

This is why in the Engine Rebuild book, I recommend using anti-seize compound, instead of motor oil as a lubricant. In this manner, you have some hope of getting closer to the factory specs, instead of a retorque after all of the oil has burned off. I feel that you do need to retorque after 1000 miles, as everything loosens up.

I do recommend a retorque on magnesium cases, but you rarely need to do it on the aluminum cases (the ones that used the Dilavar studs) as the aluminum doesn't creep like the magnesium.

-Wayne

[sammyg2]

If you try and re-torque a nut that has rust or lack of lubrication on the threads you will not over tighten it, you will under tighten it. If the friction is more than it should be you will twist it the same as when it was new, it just won't turn or it won't turn enough to duplicate the specified stretch.

In order to achieve the proper stretch on the old stud you would have to go way past the specified torque. if you don't do that re-torquing a stud without fresh, clean, lubricated threads is a waste of time except to prove the stud isn't already snapped off or ready to snap. It would be useful to diagnose a possible problem but not to make sure you have the correct tension on the head studs.
If the stud is that close to snapping off, it will do it by itself very soon. Do you want to know know or later?

On studs that see elevated temperatures over prolonged periods the best anti-sieze lubricant available IMO is milk of magnesia from the drug store. just paint it on. it will last and lubricate longer and better than any anti-sieze I've tried, and we've tried just about all of them on the market where I work.

It is all we use on $1million pieces of equipment that run at 1300 degrees F. for 5 years continuously between overhauls.

Some anti-sieze products actually cause corrosion embrittlment on exotic metals. Lead based and copper based are the worst, nickel isn't as bad.

[Randy Webb]

"Sorry, but this is not good advice! ... etc."
"If you try and re-torque a nut that has rust or lack of lubrication on the threads you will not over tighten it, you will under tighten it."

- Good points, both. Maybe we should check with ARP and Race-Ware for their ideas on this?

- It strikes me that there are two things going on: 1. stretch of the stud, and 2. twist of the stud in the case (I am a Mg case person, BTW, hence my interest in torquing these things).

IT still seems to me a good idea to torque the nuts if they aren't frozen on -- if the stud can't take the proper torque (the component that produces a shear force) then there is a problem. If it can't take the tension component, then there is still a problem. Doesn't that seem correct to everyone?