[quote=“RuiMeneses, post:1, topic:445059, full:true”]
After few months i finally put the head back in place .
I checked everything maniacally before , even the studs protrusion . All went smooth.
( This thread is related to Panic reporting - valves expert opinion needed : sudden zero compression on cylinder 2, XJ6 1985 )
BUT
I used new shiny domed nuts I bought from SNG .
Only when torquing I realised that a couple of the nuts went back 1 mm or so, when I stop exerting force on the wrench . Meaning that the stud is under torsional effort which made compare the old with the new nuts
The new nuts are 3 mm shorter (!!!) so I fear that the stud is as fsr as it can go in the nut .
I cannot compare the interior deepness of new versus old nuts without untorquing the head and removing one nut …
Tomorrow I will call SNG… This is quite messy .
Question:
(1) Is it ok to untorque the head , replace nuts and torque it again , I guess it should be done in reverse order, I am sure those studs fully in the domed nut will come out with the nut.
You sure cannot leave things as is, Rui - anything is better than that…
With the ‘spring- back’ you observed; the head is incorrectly torqued at that nut - and likely the others as well. The torque you read is just the twisting of the stud, of course.
It is, as others say, perfectly OK to release the nuts and retorque the head with the ‘proper’ nuts, one by one or all at once - but the torque sequence must be adhered while torquing. Unless the engine was run, there should be no damage done.
Using shims as suggested by Doug is OK as long as there are enough threads left in the ‘shallow’, nut to take the load. And Doug’s experience so indicates…
While ‘gradual’ torquing was prescribed, a ‘stepped’ torquing to 1/3 or half the prescribed torque on all nuts in torque sequence - the final torque to set value must be in one sweep to avoid binding, giving misleading read.
It’s also advised, depending on torque meter used, to watch the progressive increase in torque. If at any time the torque force remains constant; you are twisting the stud/bolt - and if proceeding something will break…
Adding that normal procedure is to retorquing the head after some 1500 km of driving…
Frank
xj6 85 Sov Europe (UK/NZ)