Lube on threads.. does it increase torque accuracy?

Ok. I'm installing a new set of cylinder heads with new fasteners. Should I be using a lube on the treads to get an accurate torqueing? I think i should, but Im kind of in the dark about this. What kind/brand should I get. Can I improvise, wd40, grease perhaps?

Head studs or Head Bolts?

With bolts, most us the GM teflon (it like a paste, it comes in a tube) on the threads to help keep water from passing the treads.


With head studs, you need to use lube on the threads that go into the block but not on the threads that are exposed after the head is installed.
Then you can put a sealeant on them to prevent leaks around the nut.

From ARP's website:

The lubricant used is the main factor in determining friction, and therefore, the torque for a particular installation. Motor oil is a commonly used lubricant because of it’s ready availability. If less friction is desired in order to install the fasteners with less torque, special low friction lubricants are available. With special lubes, the required torque can be reduced as much as 20 to 30 percent. It is important to keep in mind that the reverse is also true. If the torque value has been specified for a particular fastener on the basis of low friction lube, installing the fastener with motor oil will result in insufficient preload; the torque has to be increased to compensate for the extra friction caused by the motor oil.

Friction is an extremely challenging problem because it is so variable and difficult to control. The best way to avoid the pitfalls of friction is by using the stretch method. This way preload is controlled and independent of friction. Each time the bolt is torqued and loosened, the friction factor gets smaller. Eventually the friction levels out and becomes constant for all following repetitions. Therefore, when installing a new bolt where the stretch method cannot be used, the bolt should be tightened and loosened several times before final torque. The number of cycles depends on the lubricant. For ARP recommended lubes, five loosening and tightening cycles is sufficient.

Rich

What Rich posted is very good info, however on head bolts you need to use a thread sealant, not just a lubricant. Otherwise the head bolts will seep antifreeze.

What Rich posted is very good info, however on head bolts you need to use a thread sealant, not just a lubricant. Otherwise the head bolts will seep antifreeze.

I have never had this problem but some have.
It is probably due to the threads not being cycled 4/5 times or the threads in the block are missing chunks.
I have always followed ARP directions and used their lube.
I also talked to ARP about this and they said either lube will do as they make a sealent/lube for the head bolts.
This is doing Fords as well as GM with steel and aluminum heads.
Just got through with an LS1 using the TTY bolts and used engine oil and had no problems.

BTW: one's wrist can get REAL SORE assembling a motor when you loosen and tighten all of the main and head bolts/studs FIVE TIMES!!! Let's see, for a BBC that's 32 head fasteners, up to 20 for the main caps (depending on block design) and 16 rod bolts. That's 68 fasteners*5/fastener = 340 flippin cycles. I admit to cheating and doing it three times.

Rich

BTW: one's wrist can get REAL SORE assembling a motor when you loosen and tighten all of the main and head bolts/studs FIVE TIMES!!! Let's see, for a BBC that's 32 head fasteners, up to 20 for the main caps (depending on block design) and 16 rod bolts. That's 68 fasteners*5/fastener = 340 flippin cycles. I admit to cheating and doing it three times.

Rich


:shock:

:shock:

Yep, welcome to "True Confessions" of a guy with old wrists.

:cry:

Rich

Yep, welcome to "True Confessions" of a guy with old wrists.

:cry:

Rich



:lol:

They were used too much when they were new.

BTW: one's wrist can get REAL SORE assembling a motor when you loosen and tighten all of the main and head bolts/studs FIVE TIMES!!! Let's see, for a BBC that's 32 head fasteners, up to 20 for the main caps (depending on block design) and 16 rod bolts. That's 68 fasteners*5/fastener = 340 flippin cycles. I admit to cheating and doing it three times.

Rich

3 times gets you REAL close. Doubt most shops do that.

I have never had this problem but some have.
It is probably due to the threads not being cycled 4/5 times or the threads in the block are missing chunks.
I have always followed ARP directions and used their lube.
I also talked to ARP about this and they said either lube will do as they make a sealent/lube for the head bolts.
This is doing Fords as well as GM with steel and aluminum heads.
Just got through with an LS1 using the TTY bolts and used engine oil and had no problems.
I thought LS1 head bolts were blind :shrug:

So you're saying that if I cycle my head bolts (like should be done anyway) and use ARP's lube, that I would be better off than using the white sealant gunk that I've always used?

I'm in the process of assembling my new LT1 right now, so maybe now would be a good time to try another (possibly better) way...?

I thought LS1 head bolts were blind :shrug:

So you're saying that if I cycle my head bolts (like should be done anyway) and use ARP's lube, that I would be better off than using the white sealant gunk that I've always used?

I'm in the process of assembling my new LT1 right now, so maybe now would be a good time to try another (possibly better) way...?


If ya are using ARP bolts call them and get there take on it.
I have never used pipe dope on the head bolts.

I have used it, and the ARP Teflon-based sealer is apparently used interchangeably with the ARP Moly Lube to get the same torque values. At least, that's the way I understood it.

This is doing Fords as well as GM with steel and aluminum heads.

On Fords Modular motors the head studs/bolt dont go in to the water jackets.

Install per the manufacturer's recommendations. If you're unsure, call them, they have plenty of data to support their recommendations.

Good luck,


Steve.

On Fords Modular motors the head studs/bolt dont go in to the water jackets.


Ya know the MM isn't the ONLY engine Ford makes. I have been doing Fords and GM since the '60's and they didn't have the MM then.

Install per the manufacturer's recommendations. If you're unsure, call them, they have plenty of data to support their recommendations.

Good luck,


Steve.

I'm gonna call big time BS on this one... everytime I try to email or call GM
I dont get an answer or I get an "I dont know, let me get back to you".
However I believe the factory recommends SAE 30 on things like rod bolts. Torque it 3 times and that will put you real close. Of couse every bolt stretches differently.


Whenever the T2Y bolts have the fiber or nylon or whatever on them heres what I read:

http://www.engineparts.com/motorhead...iles/frame.htm

Friction Loss: 90% of the applied torque to a typical threaded joint is used to overcome friction
50% of the friction is between the threads of the fastener & threads in the block
50% is between the underside of head of the fastener and work
10% of applied torque actually stretches the fastener, applying force needed to load the joint


Thats alot of difference!