The V8 Owners Forum -

I have always assumed that any bolt that has to be tightened by turning a specific angle, was a stretch bolt and hence single use.

The Landrover overhaul manual doesn't mention putting the old bolts "in the bin!" or using new bolts, but does specify 20Nm and 80 degrees for the con rod bolts.

Is there a definite answer to this?

I have just rebuilt my 4.0 Rover engine and discussed this issue with a V8 specialist who informed me that they will re-use these stretch bolts once but just do them up to 65NM (48 lb/ft). Don't try to stretch them again.

The 4.6 uses stretch bolts that should only be used once - however some people use them more that once but is not good practice.

To get away from stretch bolts I switched to ARB studs which work well.

Garry

What you really need to ask is are they torque to yield bolts? not stretch!
ALL bolts stretch, the unknown part is where the bolt is on its stress/strain graph so you really need to rely on the manufactures workshop manual, if it states renew bolts then renew. If it doesn't then it's up to you! Personally I reused my cap bolts in my 4.6.

EVERYONE used to say to re-new the head bolts in the 1.8 rover k series - BUT in the manual Rover gave a maximum length spec for the head bolts - if the bolts are withing this spec they can be reused.

It's only a 'rule of thumb' regarding the torque to angle = torque to yield.
What is really important - and often not know is if the bolt is Torque To Yield? (TTY) bolts are designed to be stretched to a degree
that requires greater precision than can be achieved using torque measurement alone. The benefit is a more uniform amount of clamping
force being applied to the materials being joined..
Your spanner applies a 'torque' to the head of a bolt to tighten it. Tightening any fastener to an angle rather than a torque is generally more accurate/repeatable way to achieve a certain level of design stress in the fastener as it takes friction 'mostly' out of the equation.

From the Landrover 4.0-4.6 workshop manual:

. 6. Remove 2 bolts securing each bearing cap.
7. Remove bearing cap and bearing shell.
NOTE: Keep bearing caps and bolts in
their fitted order.

And doesn't mention about fitting new bolts when torquing up:

6. Fit bearing cap bolts and tighten to 20 Nm (15
lbf.ft) then a further 80 degrees.

I would be careful changing any bolts which clamp 'round things' with caps as if you are changing the clamping force you will be changing the roundness of these caps - really they should be torqued up with these new fasteners and honed/lined bored to ensure roundness.