Headbolt re-torque

[Lonnie Johnson]

Does anyone go back through and re-torque the head bolts after installing new head gaskets and heating up the engine? If so, what torque do you use on a hot engine, or does it matter?

Thanks,
Lonnie

[John O.]

Re: Headbolt re-torque

Hi Lonnie

I could be wrong but through my knowledge, torqing is done by bolt size.Whether the engine is hot or cold, it is still by bolt size. I believe it's always done with a cooled down engine. Hot and cold engine makes for expansion and contraction.After you run it for awhile, let it cool down before retorqing.You need to find what the FT. LBS. of torque are for those bolts are and then torque it to those FT. LBS. There are usually markings on the bolt heads to tell the hardness of the bolt.

John

[Joe C.]

Re: Headbolt re-torque

Lonnie:

I believe that many, or most manufacturers of composite head gaskets do not recommend, or further, even discourage retorquing the head blots. Older design, steel shim gaskets should be retorqued. Follow the manufacturers recommendations. I believe that hot/cold torque values should be the same with iron heads. As far as bolt torques are concerned, head bolts are generally grade 8, with stepped shanks. They should have been lightly greased or, better, lubricated with "Thread Sealer With Teflon" before insertion. Torque using the following link as a guideline:

http://www.sizes.com/tools/bolts_SAEtork.htm

I have Fel Pro composite gaskets installed in my SBC. I did not retorque mine. All engines that I have assembled using composition gaskets have never been retorqued. There has never been a sealing problem to date.

Joe

[Michael H.]

Re: Headbolt re-torque

Lonnie,

Head bolt retorque for steel shim head gaskets is not required, or recommended. In fact, it is strongly recommended that they not be retorqued.

As far as composition head gaskets, I believe the heat cycle retorque has pretty much been eliminated years ago. The newer design does not require retorque.

Some form of sealer should be used on the threads of all the head bolts as they go directly into the cooling system.

Michael

[Lonnie Johnson]

Re: Headbolt re-torque

Thanks guys for your answers. Helpful indeed!! An ole guy like me that hasn't rebuilt an engine for quite a few years gets out of touch with newer materials and practices. Looking at the available head gaskets, either shim type or composition, I can see how re-torqing is not necessary, but just wanted to make sure.