Proper procedure for re-torqueing head studs

[brokenspoke]

What's the correct way to re-torque heads? Some say to back off stud and torque again, others say just check torque.

[alexiskai]

I think the longer you've gone between re-tightening sessions, the more important it is to back off a few degrees before tightening, because corrosion may have formed that causes the nut to stick despite having a low clamp load. Under ideal conditions, meaning that the fine threads on the nut are lubricated and you're doing run-in on a new head after just a couple of hours, probably either way is fine.

[PotvinV8]

I think the idea of retorqueing the head fasteners after a few heat cycles is to ensure the proper clamping force is being applied after all the components have had a chance to do their thing due to thermal expansion. That said, if the fastener is backed off and then retorqued, you've effectively started the process all over again.

Good practice would be to check the torque of each fastener periodically following the sequence found in the Ford Service Manual.

[nkaminar]

I don't back the nuts off before re-torquing. I use a anti-seize compound on the studs when first installing the nuts.

There is a certain amount of stiction, which is static friction, which is larger than the sliding friction. So the nuts may not move at the specified torque. But they are probably tight enough if they don't move.

If the head has not been torqued in a while and the studs/nuts are rusty then you probably should back them off or remove them one at a time and add some anti-seize. Drain the coolant first. In the worse case you may have to remove the head and replace the studs and nuts. Some on the forum will say that removing one nut will cause the gasket to leak at that point. But the gasket is probably bad anyway if that happens.

Torque the head with a cold engine and go up in 10 foot-pound increments. Too much torque on one stud without the others torqued can cause a crack in the block or head.

[Gary WA]

Model A Ford Garage ~ Brumfield Cylinder Head Gasket Instructionss

[Gary WA]

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Follow the late Larry B instructions you will never have a head gasket problem. Do exactly what is said.

[AL in NY]

nkaminar: anti-seize should NEVER be used if you are torquing to a prescribed value. The nut/bolt should be torqued dry to achieve the correct clamping force as denoted in the torque specification.
When retorquing you should ALWAYS back off the fastener 1/8 of a turn and re-torque to the recommended valve so the sticking friction does not figure into the final torque value.

[Chris Haynes]

Originally Posted by AL in NY

When retorquing you should ALWAYS back off the fastener 1/8 of a turn and re-torque to the recommended valve so the sticking friction does not figure into the final torque value.

I would like to know what manufacturer recommends that so I can look it up.

[AL in NY]

Larry Brumfield. I have always used his procedure and it's never failed me. I have had his 5.9 head since 2006.

[Pete]

Originally Posted by AL in NY

Larry Brumfield. I have always used his procedure and it's never failed me. I have had his 5.9 head since 2006.

The Brumfield method works not only on flathead 4 bangers but V8's and OHV engines also.
Here is some other info people installing studs and heads should know.

Here are few things to think about for head studs.

A thread to be properly used needs to be CLEAN bare metal.
No corrosion, rust or scale. Any of these will corrupt a torque reading.
A thread chaser is essentially an under size tap or die that will clean out MAJOR rust and corrosion. This device can not produce a correct size CLEAN thread. Like it or not, the laws of physics apply here.

Head stud holes in a block need to be cleaned with a standard tap which will make the thread size as it came from the factory. This operation needs to be done with a fixture that holds the tap in perfect vertical alignment or a machine such as a mill or large drill press.
If the hole does not clean to bare metal then it is too rusted/corroded to hold proper torque and needs to be repaired.
While sometimes not visible, corrosion can account for up to 20% corrupt torque readings before the thread fails.

A sealer such as high temp. RTV can be used on the course end but a thread lube absolutely must be used on the fine thread end. The lube can be a HYPOID gear oil or ARP thread lube. The RTV sealer on the course end should be allowed to dry for at least an hour before assembly.

Head stud holes in a block can be tested before final assembly of the engine with simple home made tools. A 3 inch diameter by 2 inch thick hardened steel slug (BOTH ENDS PARALLEL) with a 7/16 inch hole in the center, a HEAVY HARD steel 7/16 washer, a HARD high nut and a proper length stud. You install the stud through the slug with the lubed nut and washer on top and torque to 80 for a model A or flathead V8. If the thread is good, the torque wrench will have a solid feel. No “floating” or wanting to keep turning. You can re-use the nut many times.
Good threads will easily go over 100 if you are wondering.

[nkaminar]

Pete, thanks for the post. I use thread sealer for the studs because none of the holes go into the coolant passages. On my old engine one stud for the manifolds went into the coolant passage and I used the RTV sealant there.

While it is true that lubricant will reduce the torque needed to achieve the same stress on the studs, the increased stress with 55 foot pounds of torque is not enough to break them if they are grade 5 or 8. I read somewhere that the anti-seize does not have the same lubrication qualities than say motor oil or gear lube. There are two schools of thought on whether to torque the nuts dry or lubricated. I like the idea of using anti-seize because it makes it much easier to take the nuts off, especially if they have been on for years. Plus the amount of friction for the dry nuts can be all over the place so you really don't know what you have.

I worry about cracking the block if too much torque is applied to one stud. Terry Burtz recommends 10 foot-pound increments and bringing up all the nuts in a uniform manner to avoid the chance of cracking the block. He is talking about how the head gasket compresses so it does not apply to your testing technique using the 3 inch steel slug which you use without any gasket.

[Pete]

Just as a side note, hypoid gear lube is a "unipolar type lube". Several other lubes for other automotive use are of this type.
Basically what it means once you apply it to a HARD bearing surface, the only way to get it COMPLETELY off is to grind or acid etch the surface. No solvent will get it all. That is why they use it for hypoid rear ends where tooth pressure is much higher than in a conventional one.

[alexiskai]

Originally Posted by Pete

Head stud holes in a block need to be cleaned with a standard tap which will make the thread size as it came from the factory. This operation needs to be done with a fixture that holds the tap in perfect vertical alignment or a machine such as a mill or large drill press.
If the hole does not clean to bare metal then it is too rusted/corroded to hold proper torque and needs to be repaired.
While sometimes not visible, corrosion can account for up to 20% corrupt torque readings before the thread fails.

You're applying logic from the V8, which uses bolts, but the Model A uses studs. When you tighten head nuts on the Model A, torque is being applied to the fine threads at the top of the stud, not the coarse threads in the block. The block threads don't need to be smooth, they just need to hold the clamp load placed on them by the action of the head nut forcing the head against the block. The stud doesn't slide against those threads. If you tap them, you're just excavating material that can't easily be replaced.

Testing head nuts on the Model A at 80 ft-lbs is a waste of time, you learn nothing more than you would by torquing them to the value you intend to use for your head installation. And you might strip threads that would have held at the regular clamp load.

I wouldn't re-use nuts if you can help it. The nut is designed to be softer than the stud, so it deforms as it tightens. There are studies showing that each time you re-use a bolted joint, it takes more torque to obtain the same clamp load. Also the nuts are cheap, it's like fifty cents each. Buy a bag of nuts for testing.

[Pete]

Originally Posted by alexiskai

You're applying logic from the V8, which uses bolts, but the Model A uses studs. When you tighten head nuts on the Model A, torque is being applied to the fine threads at the top of the stud, not the coarse threads in the block. The block threads don't need to be smooth, they just need to hold the clamp load placed on them by the action of the head nut forcing the head against the block. The stud doesn't slide against those threads. If you tap them, you're just excavating material that can't easily be replaced.

Testing head nuts on the Model A at 80 ft-lbs is a waste of time, you learn nothing more than you would by torquing them to the value you intend to use for your head installation. And you might strip threads that would have held at the regular clamp load.

I wouldn't re-use nuts if you can help it. The nut is designed to be softer than the stud, so it deforms as it tightens. There are studies showing that each time you re-use a bolted joint, it takes more torque to obtain the same clamp load. Also the nuts are cheap, it's like fifty cents each. Buy a bag of nuts for testing.

There is so much misinformation and plain LACK of information in that post, I am going to let someone else handle it.

[johnneilson]

Originally Posted by Pete

There is so much misinformation and plain LACK of information in that post, I am going to let someone else handle it.

Not me, I'll just leave it to the Old Wives Tales.

J

[Pete]

Originally Posted by johnneilson

Not me, I'll just leave it to the Old Wives Tales.

J

Giggle......ROFLMAO...

[nkaminar]

The important part is that the block has good treads instead of rust.

The instructions in the red book say to finger tight the studs and not to then back them out 1/4 turn which some people do.

If you need to drill and tap to add inserts because of damaged threads, use an old scrap head as a drill guide and drill out the holes in the head as needed. Bolt the head down at a couple of locations. I have used Heiicoils with good results although some people don't like them as well as other inserts.

A flat sheet of glass can be used to check the flatness of the block. Smear bluing on the glass and then rub it on the block. Where it does not transfer are the low spots and where it does transfer are the high spots. The glass lets you see what is going on. In my auto shop class in high school the instructor set me to work to deck a block with a file. I think he just wanted to keep me busy. Is auto shop class still offered in high school or has it been replace by engine management computer programming class?

[katy]

Originally Posted by alexiskai

You're applying logic from the V8, which uses bolts, but the Model A uses studs.

The flathead V-8s used studs up to and including 1948, starting w/the BA and CM series in 1949 is when Ford went to "bolts".

[alexiskai]

Originally Posted by katy

The flathead V-8s used studs up to and including 1948, starting w/the BA and CM series in 1949 is when Ford went to "bolts".

I stand corrected. My point is still valid: Pete’s reasoning that the block threads must be cleaned *because it will throw off the torque* makes no sense.

[rotorwrench]

I take a 7/16 bolt an cut two flutes in it with a cut off wheel then chase the threads with it. I cean all the crap out with spray cleaner and compressed air. I use the method Murray Fahnestock used in an old Restorer magazine article from 1961. Since the model A head stud threads have a bottom, I hand tighten the studs in the block. Getting new studs adjusted so the gasket will drop on can take a bit of pulling on a stud or two but it has to drop onto the deck. Paint the new copper sandwich gasket with copper or silver paint then drop it and the head on. I paint the copper water neck gasket and drop it and the neck on. If you want the electro lock clamp on then it has to be installed before torquing the nuts. Put some oil on the bottom of each nut then install all of them to hand tight. Torque in the Ford recommended sequence to 25 ft/lbs. Final torque in sequence to 50 ft/lbs. Follow up with several retorques after heat/cooling cycles.

There are variations depending on what heads or gaskets are being used. Use a washer under the #8 stud if the electro lock clamp is not used or use a shorter stud. Some folks use a thin gasket or just sealant on the water neck. Use what you feel comfortable with.

On the V8 59 or earlier blocks studs are different. Most go into the water jacket. The threads have to be tight and sealant applied or they will leak. I don't ever use a tap on these threads or a person will need oversized studs. Use a loose chaser or an old bolt with flutes to clean them.