head torquing

daveymc29

daveymc29

Well-known member
I have read a lot on torquing the heads. The question that remains in my mind is this done with the engine hot or after it has cooled down? I have run my new reconditioned engine for several hours now and though it is only about thirty miles, it has been many cycles of cold to hot and then I have checked the torque after a drive a couple of times. Always "clicks" at 55 psi, never have had any movement of the nut. Standard head and bolts.
 
daveymc29 said:
I have read a lot on torquing the heads. The question that remains in my mind is this done with the engine hot or after it has cooled down? I have run my new reconditioned engine for several hours now and though it is only about thirty miles, it has been many cycles of cold to hot and then I have checked the torque after a drive a couple of times. Always "clicks" at 55 psi, never have had any movement of the nut. Standard head and bolts.
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Davey, Try it HOT, then try it STONE COLD & I think your question will be answered.
On Minerva, ONLY ONE bolt took torque when HOT, when she was STONE COLD, all except that one took some torque.
I, personally, NEVER loosen them when re-checking the torque.
Bill W.
 
Always COLD!Backoff 1/8 as stated then retorque in sequence.
 

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First time hot and I'm not expecting it to hold final torque when I retorque it the first time. I retorque hot the first time because you lose so much torque between installation and the first retorque (after about 20 minutes) that you run the risk of water entering the combustion chambers. After it cools completely, I retorque again. I then continue to retorque cold at entervals untill it holds 55 ft. lbs. torque.
 
Thanks, I'll re-check it tomorrow morning when it is totally cold. Then I'll do it after my first oil change. I'll do the back off 1/8 as that's logical to me. Have not do that in the past, but it makes totally logical sense to me. (Easily swayed).
 
James Rogers said:
Always when it is cold. This allows the metal to contract to it's smallest size and will assure a proper clamp.
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James, with your credentials, "maybe" folks will listen to YOU. I only, ever post "help" that has worked for me, personally:) & I've done this crap for EONS!!
Bill W.
 
This is like the oil questions.
Some like it hot (Ford suggested hot) some like it cold. Dreamwerks, that makes it money building engines today, says cold.

I was told years ago that the reason for the "hot" torquing is that the bolts expand when hot so if it is torques to 55 hot when it cools off they shrink again and the actual torque is now actually greater then 55.

The most important thing is to repeat the sequence several times to be sure that the gasket is as compressed as it can be.

Want more fun, ask if the head nuts should be cracked loose slightly before re-torquing.
 
Yes more fun ! The only man who ever made heads for our A/B engines in not too distant past, Larry Brumfield, developed/recommended the 'backoff' method !
Who was Larry Brumfield that he should know how heads should be torqued...lol
 
I think a person should satisfy their own curiosity. Try to tighten the nut with 55 lbs., then using a torque wrench, see how much torque it takes to break the nut loose while backing off 1/8 turn, then retighten to 55 lbs, and look at the flat on the nut to see if it moved any.
 
Mike V. Florida said:
This is like the oil questions.
Some like it hot (Ford suggested hot) some like it cold. Dreamwerks, that makes it money building engines today, says cold.

I was told years ago that the reason for the "hot" torquing is that the bolts expand when hot so if it is torques to 55 hot when it cools off they shrink again and the actual torque is now actually greater then 55.

The most important thing is to repeat the sequence several times to be sure that the gasket is as compressed as it can be.

Want more fun, ask if the head nuts should be cracked loose slightly before re-torquing.
Click to expand...
Mike, you are correct in all you state EXCEPT, this,"I was told years ago that the reason for the "hot" torquing is that the bolts expand when hot so if it is torques to 55 hot when it cools off they shrink again and the actual torque is now actually greater then 55." It is my understanding that there is only one material in existence that expands when hot or cold and that is water. Everything else expands with heat and shrinks with cold. This means when the metal heats, the gasket gets clamped more because of expansion. When the metal cools the clamp is released some because of shrinkage so, the nuts will need to be retorqued when cool for a better, more reliable reading. Remember, heating not only expands the studs and nuts but, also the head and block.
 
My grandfather tried to teach me the "old timers method" of tighten it till it screams then go 1/4 turn more. I now know better. I don't have any head gasket failures so, I'll stay with my method.
 
hardtimes said:
Yes more fun ! The only man who ever made heads for our A/B engines in not too distant past, Larry Brumfield, developed/recommended the 'backoff' method !
Who was Larry Brumfield that he should know how heads should be torqued...lol
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Larry didn't 'invent' the backoff method. It is standard practice for any critical fastener torque and based on a sound physics and engineering proven principle. Simply put, starting and sliding friction are two different things.

The force necessary to start a stationary object sliding is greater than the force required to keep it moving at a constant rate. LINK

A fastener torqued to 50 ft/lbs may require 60 ft/lbs to start it moving again, so a torque wrench showing 55 with no movement will yield a false indication. Thus the 'back-off' to permit a true sliding reading to final torque.

FWIW, if you actually READ the instruction sheet that comes with many quality torque wrenches, it will say the torque to final desired reading should be done in one continuous pull, with no stops or hesitations. Yet another reason why I much prefer moving beam wrenches over 'click' types. You can see when you are approaching the desired torque.

So, to answer your question (...lol), Larry is a guy sufficiently schooled in engineering physics who knows how to use a torque wrench.;):)
 
Does anyone still put paper match sticks under corners of upper water inlet so as to prevent cracking the tabs on neck?? I have as yet to torque this water neck which is part of head torque... maybe some gasket maker instead of paper gasket?? What do you think??
 
LopezCarguy said:
Does anyone still put paper match sticks under corners of upper water inlet so as to prevent cracking the tabs on neck?? I have as yet to torque this water neck which is part of head torque... maybe some gasket maker instead of paper gasket?? What do you think??
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Don't use the paper gasket which can get wet and squeeze down, allowing the ears to crack.
I've had good luck with the copper gasket and also with no gasket, but using a sealer.
 
To All,
Everyone should follow their own conscience, gut feeling, or whatever has worked well for them. There are a lot of variables & lots of differences in head gasket constructions & lots of different things go on, from cold to hot & back to cold again & remember, we're dealing with some old iron, & a bare minimum amount of head studs.
Bill W.
 
Hey Mike,
Good read and all seems to support what I 'learned' from Larry :) ! Who the heck has written instructions with an old 'beam' torque wrench anyway ..lol
I have several different makes (antiques?) that I was going to give away, and now you have changed my mind about that. Larry may not have 'invented' the method that you and I are familiar with, but he is the first guy that I've ever seen who advocated that process on the old Barn. I've used it, after reading him, and use it today pretty successfully, IMO.

For those who have not tried the 'Brumfield Backoff Method (my name for the process). Give it a try and you will be amazed at the results. Just when you think that you have attained the torque that you seek, you may be surprised..pleasantly. Mike K and Larry , knowing physics of the idea, and can expound on that. But, my eyes, no leaks and no more torqueing seems to be needed.. can tell me it works. This is how. I mark each head nut on one land/head with marker. Back it off a half turn or less...then with one clean full sweeping motion...bring the torque up to what you want. Now look for the land mark on nut and mark on head..what the heck :D ! Caveat...only ONE nut at a time tho, in proper sequence. And, this method is after all have been torqued/cycled and ready for 'final' torqueing.
 
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