5 replies to this topic

[Abbot]

Now I am confused. I am rebuilding my engine and have just Torqued up the head to the values shown in my Haynes manual.  The values are for first stage 25 lbf ft and then the final stage of 50 lbf ft  .  The data sheet at the start of this thread shows 40 lbf ft as the final stage.

 

When I did apply 50 bf ft it was obvious to me that the resistance was not increasing and the wrench did not click.

So I think I have over stretched the bolts and not achieved the torque.  

 

Any ideas why the Haynes manual can be so wrong? or have I done something else that is stupid like oil on the threads.

 

 

[KernowCooper]

Dry threads when doing the head bolts

[Swift_General]

50 lb ft should be fine (dry). It's the figure I use, torqued up to 25 first although others go to a lesser figure. If you have oiled the threads then you are effectively tightening them further. Less friction on the threads and nut face will mean that the stud will be stretched more for any given torque as less of the torque applied is needed to overcome friction. If you are happy your torque wrench is correctly calibrated and in doubt then change the studs. They are cheap enough.

[Abbot]

Thanks for the feedback it confirms what I had already concluded.

What is the best to degrease the bolts?  Petrol??

Edited by Abbot, 08 February 2017 - 10:28 PM.

[RooBoonix]

Thanks for the feedback it confirms what I had already concluded.
What is the best to degrease the bolts?  Petrol??

I'd spray a rag with brake cleaner and wipe them over. I guess petrol would work too..

[sonikk4]

Brake cleaner or petrol will do the job nicely.