Quote:
Originally Posted by basuni90
Ok thanks! And was it only one additional 90 degrees or two?
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One additional 90 degrees.
The initial torque puts the bolts in tension and stresses the molecular lattice of the aluminum. It will settle a bit after a rest period, which is why you verify the torque after the rest. The 90 degree final turn takes the bolts into the yield strength stress on the aluminum which gives a consistent tension on each of the bolts. Going further takes the aluminum into ultimate tensile strength forces which is where you have snapped them in two.
Because you take the bolts into the yield strength region you can only use them one time. If you try to reuse them, you'll find the ultimate tensile strength has come down and you risk either snapping them when you do the final 90 degrees or having them fail on their own the first couple of heating/cooling cycles of the engine.