BryO

I got the head back from the machine shop and I have been reading the manual to make sure that I get this right. But the torque language is killing me. I have done many Ford and Chevy rebuilds in the past but what the heck is torque to 15 lbs and then 90 drgrees and 90 degrees again.

I understand the waiting but what is it talking about 90 degrees? Turn the bolt another 1/4 turn and wait 15 minutes and do it another 1/4 turn?

Techno Duck

Yes, torque to 15 ft-lbs. Wait aprox. 30 minutes, turn nut 1/4 turn, wait 30 minutes, then turn 1/4 turn again. The correct way to do it is with a torque angle gauge, but you can get away with marking the nuts with a sharpie.

BryO

Thank for the reply. On it now.

Porsche16V944

stretch bolts.... which means dont reuse the old bolts

jcslocum

All bolts stretch when tightened properly. Are you saying these bolts are single use bolts/studs and need to be replaced after each use??


BTW, angle of turn is more accurate (normally) than torque. AOT does not have to figure in friction in the threaded surfaces or under the head of the nut. The first torque value is to set the joint and zero it out. The the 180 degrees of total rotation should all be stretch. For example, if you have 8 threads per inch on your stud and after the joint is firm, you rotate the nut 1 full turn, you will have stretched the stud 1/8" longer. If torque is used then the engineer has to try and figure out how much or what % of loss there will be. Very hard to do and the scatter in a typical joint is +/- 25% when torqueing.

Jon

Van

Bolts/studs only need to be replaced if they've been stretched past their point of elastic deformation (where they'll spring back to their original shape). The point after elastic deformation is called plastic deformation... and when bolts reach that, they will fail.