Lubricate Head Nuts?

[29 Tudor]

I've searched the forum and can't find a definitive answer to this question. Les is silent on the subject. Should the nuts (and head surface) be lubricated before torquing and if so, what do you use? I'm thinking anti seize would be a good choice but I don't want to alter the compression of the head gasket.

Thanks in advance for the information.

Steve

[redmodelt]

I do them dry.

[RonC]

No torque dry.

[Jim/GA]

A small drop of oil on the head surface where the nut touches when you tighten it is OK, but no oil on the threads (if you are going to use the recommended torque values, because they assume dry threads).

[Joe K]

I do them lubricated. And hot.

Lubrication makes for more consistent tensioning. And it will result in a higher translation of torque to tension.

The SAE torque charts show (IIRC) values for torque given either lubricated or dry.

http://www.docstoc.com/docs/4862329/...ssembly-Torque.

I have broken a head stud. Actually the stud broke during tensioning and not the connection to the head. Admittedly my heart was in my throat when it happened - but I was able to remove the head and grab what remained of the stud with a pair of vise grips and turn it out. (It broke at the bottom of the upper threaded portion.)

Generally I want to stress my bolts to the maximum that I can bring them to - if they will survive torquing, then they will not fail in service. Torquing brings to a fastener to the WORST conditions it will ever see in it's life.

And, per my previous discussion of torquing, the studs actually "tighten" in the head as they cool.

See https://www.fordbarn.com/forum/showth...ead+nut+torque and read the whole thread.

Joe K

[Purdy Swoft]

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I agree with Jim Cannon. I use anti seize compound on the stud threads where they enter the block to prevent sticking later. I only tighten the studs hand tight with a pair of Ford pliers . The head nuts need friction to obtain the 55 ft. lbs. torque. If the upper end of the head stud threads are oiled, they will more likely strip before they could reach 55 ft. lbs. torque.

[ford3]

lubricated head bolts or nuts do not need as much torque as dry nuts or bolts, dry nuts or bolts give you torque values needed to over come dry and binding threads, so not an accurate binding force reading on head gasket

[nick c]

Hi Steve, I have a Les Andrews book and the information is all the way in the back, it's called the appendix, on page A-4, Bolt-grade/torque comparison. The answer to your question is dry. If you use a lubricant, you should reduce the torque anywhere from 25% to 45% according to the book.
carry on nick c

[29 Tudor]

Nick C,

Thanks! I looked al through the book and never saw that. I appreciate it!

Steve

[Mike V. Florida]

Originally Posted by 29 Tudor

I've searched the forum and can't find a definitive answer to this question. Les is silent on the subject. Should the nuts (and head surface) be lubricated before torquing and if so, what do you use? I'm thinking anti seize would be a good choice but I don't want to alter the compression of the head gasket.

Thanks in advance for the information.

Steve

Looks like there still is no "definitive" answer.

[Purdy Swoft]

If the upper threads are oiled you will have to reduce the torque or strip the threads. I've seen the figures for oiled threads but don't remember the exact figure, it is probably around 50% or slightly less. If you plan to torque the head nuts at 55 ft. lbs. as recommended , don't oil the threads or you will strip the them . Oil is good in its place but will make a mess if overly applied or used in the wrong place.

[29 Tudor]

I appreciate all the answers. Clearly a lubricated thread will apply more stretch to the stud and since the specification of 55 ft./lb. was apparently arrived at with dry threads, I will not lubricate the nuts or nut/head interface. I WILL re-torque several times until there is no more movement.

Thanks again for the excellent responses.

Steve

[Greg out west]

Hi guy's


Am I missing something here..I've always lubed the thread's & never had a problem stripping the thread's...Here's the question ??? If using a Click to torque wrench won't it release at 55 lbs no matter wet or dry ? Also as the engine goes thru many hot & cold cycles the lube goes away to a great degree,,,


Greg out West,,,

[Joe K]

Like you I have not had issue with using lubricant - and common sense.

And yes. A click is a click to a torque wrench.

Those who use not lubricant usually torque to a higher number - and also subject their head studs to greater torsion. But torsion is not what you're looking to do. Tension is the desired objective. And using lubricant DOES reduce the residual torsion and increase the effective tension of studs/nuts.

In my turbine/boiler feed pump working life I saw a neat system for tensioning nuts used on a lot of the larger machine bolting. It's a system which includes a main nut which is applied only hand tight - but then a ring of bolts around the periphery of the nut are tightened according to their chart to achieve a certain tension on the main stud. The small bolts are tightened similarly to the nuts on a wheel hub (in a star pattern of sorts) but this to prevent "tilting" of the main nut - and subjecting the main stud to bending stress - or torque.

It's nearly ALL pull in this case.

Ideally that is what you want on an engine head.

But there are many ways to do it.

Joe K

[Mike V. Florida]

Originally Posted by Greg out west

Hi guy's


Am I missing something here..I've always lubed the thread's & never had a problem stripping the thread's...Here's the question ??? If using a Click to torque wrench won't it release at 55 lbs no matter wet or dry ? Also as the engine goes thru many hot & cold cycles the lube goes away to a great degree,,,


Greg out West,,,

Friction, that is what you are missing. With lubrication the actual toque value is greater than what the wrench is telling you. There are charts on this if you want an actual value.

Take a car on drive pavement, how much force do you have to apply before it moves? Take the same car and put it on ice, how much force do you have to apply before it moves? Same idea.

[Hicktick]

Think about it this way , down at the engine plant after all the machining you think they cleaned the threads dry before they installed the head ???

[hardtimes]

Hey Joe K,
Your learnin and experience...ain't worth spit and won't convince no body, of course, except the likes of me !

Too bad that there isn't (or maybe there is ?) a detailed video demonstrating this (lube/no lube) 'conflict' relative to head studs, etc. !
But then, some have to put their finger into the 'wound' anyway,eh.

A guy could look at this thread another way maybe...it combines the very controversial OIL USE subject and the very controversial TORQUE USE subject ..and disposes of both in one swoop !

Joe, I have another question. Why do guys use OIL on main and rod studs/bolts to torque them

[MALAK]

While I have no problem with the time tested 55lb method I believe there is a better way and here's why:

1) The torque applied to the nut is the result of the stud resisting being stretched and the friction generated at the threads/nut/head interface.

2) The purpose of torqueing is to stretch the studs providing a uniform clamping force across the cylinder head/block interface.

3) The friction at the threads is highly variable and with a given torque results in an inconsistent (variable) preload from one stud to another. Tests have shown that the friction and subsequent clamping force are variable and inconsistent after multiple cycles (re-torqueing). Using oil, anti-seize, moly, and other lubricants not specifically developed for torqueing reduces friction but can actually make the inconsistency of clamping force from one stud to another worse.

So I use ARP Ultra-Torque Fastener Assy Lube and use the reduced torque value as found posted in the chart by Joe K.
ARP Ultra-Torque is specifically designed (and tested) for torqueing applications and provides consistent clamping force from the first installation through repeated re-torques and consistency from fastener to fastener (stud to stud in this case).

http://arp-bolts.com/p/arpultratorque.php

Tom

[Joe K]

Arp are those who make the high tensile head studs for the VW Diesel - along with even higher end cylinder head fasteners.

And I'm not trying to convince anyone of anything - you do what you find works for you.

Ford provided a wrench with a socket that fits the head nut - and he would have said "I've given you everything you need."

And mostly he was right.

Joe K

[CarlG]

I have ARP studs in my engine.