Re torque

Kenneth R Ohnstad · May 19, 2012

When re-torqueing the head bolts, do you do it when it's hot or let it cool.
I asked this question on another thread, but could not find the thread.
good luck
k

ohiojim · May 19, 2012

torque to specs. cold, then run till warm and retorque in sequence,...you'll be good to go...

buickanddeere · May 19, 2012

How do industrial, farm and highway diesels operate for 100,000"s of thousands of miles and thousands of hours. From out the factory door without a re-torque?

Texasmark1 · May 19, 2012

Agree. Used to way back when. I think a Chev small block, 283 was the last I did. I had the restoration all cleaned up and nice looking, and even with the little plastic spring clips you put on the valves they still slobbered all over everything.

That was it and haven't regretted it.

Mark

730d se · May 19, 2012

I figured they ran each engine after assembly and possibly before install. Then they retorque with the automatic multi heads that do all bolts about the same time.
If not, it is interesting how they get them sealed properly with one cold torque.

David G · May 19, 2012

B&D, I agree with you, retorque is a waste of time.

NCWayne · May 19, 2012

I've built alot of engines over the years and rarely do I retorque the head. With construction equipment, there are many times when it's impossible test run the engine before it's back in the machine do to hydraulic pumps, etc, etc attached to it. Then when the engine is back in the machine and completely assembled you can't get to the head bolts, (((and often can't even get the valve cover off))) because of turbo lines, fuel lines, and pretty much anything else you can think of being in the way. Some engines have so many things in the way once runnable that it would require several hours and another $100 worth of gaskets to disassemble and reassemble to do a retorque. What I have found is always go to the upper end of the torque specs, and always run the torque pattern to full torque at least twice to insure every bolt is staying at the proper torque as the others are getting pulled down compressing the gasket. Like I said, I've built alot of engines and never had a problem with any of the ones that didn't get a retorque after running.

Spook · May 19, 2012

I know GM uses a torque to turn. They go to a initial torque, then so many degrees past that.

Stuart · May 19, 2012

Some engines require torquing again. Seen it in overhaul manuals.

Bob Bancroft · May 19, 2012

When I worked at an AC dealer in the late 70's, we got a service bulletin that said to just add 10% to the torque specs. for the 301 engine (150 ft-lbs I believe) Instead of all the fussing around re-torquing a hot engine.
What's really important is the pattern, and going over them until they are all really to the proper torque. And I think more and more are torque, then turn a certain amount.

Kenneth R Ohnstad · May 19, 2012

Thanks,
I'm just getting to put a H.D. bike back together, I've done this before... it's pretty easy to get to the head bolts and upper motor mount. That's not a problem. I was just thinking about the basic properties of the metals.
I haven't done this for maybe 25 years but I think the 'book' calls for it.
Thanks again
k

Texasmark1 · May 20, 2012

Sorta like they spec their lifters: Fill lifter with oil in a can by pumping the cylinder while submerged till firm.

Install in engine and after head is torqued, run rocker arms down till they touch then 3/4 turn more to pre-load them.

On what you see in manuals, you have to remember that the data in there can be 50 years old. You and I both know that a lot of technology has come into play in materials and lubricants since then that make for longer life engines and easier for the tech.

Mark

Mark

SparepartsTN · May 20, 2012

Kenneth,

I don"t know which H.D. engine you are working on, but if you go to:
http://harleytechtalk.org/htt/index.php
you can get a lot of knowledge on the forums and in the knowledge base. I have a Panhead, but all engines are well represented there. The general consensus is torque, then run it to temp, let cool and torque again. After a hundred miles or so torque again just in case.

Warren

Re torque

Kenneth R Ohnstad

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ohiojim

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buickanddeere

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Texasmark1

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730d se

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David G

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NCWayne

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Spook

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Stuart

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Bob Bancroft

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Kenneth R Ohnstad

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Texasmark1

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SparepartsTN

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