Head re torque

[Richard71]

Perhaps Neil is using ARP cyl head fasteners. I fitted them and I'm sure they came with a note telling the user there is no need to re-torque, but hey for all the time it takes there's no harm in checking.

 

Richard.

[marki]

Thanks for the input guys, so when and if re torque is required, should it be hot or cold ?

I have been told cast iron heads should be done hot.

Cheers again Mark.

[astontr6]

I have never had a block crack due to re torquing on 1.6, 2.0 and 2.5 six cylinder engines and 948, 1300, 1500 four cylinder engines over the last 50+ years. You are only ensuring the torque hasn't reduced, if it has you then set it up again to the correct figure. This was a Standard Triumph (ST) laid down process. If it was cracking blocks ST would have stop stipulating this requirement and found another way of dealing with the changes in torque.

 

If you don't check the torque and it has reduced then the gasket may blow and or the head could warp.

 

Bolts stretch, the gasket compresses, things change after use which can cause the torque to reduce.

 

Dave

Nobody here has mentioned that the Cylinder Head and Block faces must be flat i.e. each within .002" The Triumph 6 Cyl Engine was notorious for warped blocks, valve seats/loss of compression and warped heads. If you cross section the block and cyl.head of an early engine v a later 1972 engine you would be surprised at the difference in the cast iron thickness difference in crtain places and web design. This was the reason why the counter bored block around the bores came into being and the different head gasket design. B.L. had too many warranty claims on this subject!

 

Bruce.

[oldtuckunder]

Factory torque settings are cold and also dry, which of course the ones under the rockers won't be after 500 miles. So interesting conundrum trying to calculate what torque to use on which studs even more so if hot. So its either Neil "leave it alone", or as others appear to do just re torque using factory figure and say" that will do" makes me glad I reuse head gaskets whenever possible as they don't need re torquing.

 

Alan

[pinky]

hi my handsome friends,

 

 

Well I have completed 3560 miles since rebuilding the engine, I should have re torqued after 500 miles.

I just forgot to do it,

 

do you think I should do it now yes or no cold or hot

 

I had in mind to re torque cold when I finish the upgrade on the wiring

 

 

pink

[Nick Jones]

Re-torque cold if you are going to.

 

I always do. Sometimes after just a couple of heat cycles, sometimes as long as 1000 miles. Working in the tightening sequence, back each one off 1/2 turn then tighten to the book figure. If you are anal enough to mark the nuts you'll find you "gain" ~ 1/8 to 1/4 turn, which suggests to me it's a worthwhile exercise.

 

Nick

[marki]

Cheers Nick, Makes sense to me.

[jamesStag]

Hi All, yup +1 for re-torque here too.

 

Pink, I also suggest you do re-torque when you get the chance.

 

Myself and father have done many engine heads over the years. Not TR6s granted but we've certainly had a premature failure on an engine that missed a re-torque.

 

Whilst I know NTC has lots of good advice, on this one I can't see how a re-torque results in a cracked block. Something else must be going wrong as I can't see how re-torque back to the factory setting can overload something and result in a failure. In my humble opinion either the torque wrench is faulty and overtightening, or perhaps one other possibility is either too much lubrication is applied to studs in the block or previous debris has not been cleaned out such that on tightening the stud hydraulics into the block. This would both reduce the head clamping force and the hydraulic pressure could cause the block to crack.

 

A recent experience to support re-torque is a Fordson super major diesel we've just done. On head reinstall and correct torque after a couple of runs we noticed the cold engine had a coolant external weep/leak at the head joint on both sides. So re-torque done all studs turn further after a back off and re-torque and this then solves the weeps. Engine running fine... All seems good to me.

Cheers, J.