When to re-torque manifold nuts?

[Oldmogman]

Can anyone remind me when I need to re-torque the manifold nuts - I've covered about 250 miles since fitting a new LCB exhaust manifold, so about 15 heat cycles. Thought it was about 500 miles but can't find anything to support that!

[svenedin]

I treated mine like cylinder head nuts. Checked torque after 1 heat cycle then after a few hundred miles. I don't think it's in any way critical when you do it.

Stephen

[philthehill]

I know of no instruction relating to the re-torqueing of manifold nuts especially LCB manifolds.
Just re-torque them when it is convenient. The re-torqueing of manifold nuts is not the same as re-torqueing the cylinder head nuts where the head gasket becomes compressed which then reduces the grip /loading of the stud/nut. The material used in the manufacture of manifold gaskets does not compress to any degree so the need for re-torqueing is greatly reduced or eliminated. Saying that it does not do any harm to re-torque the nuts.
It does help manifold gasket longevity if the gasket is smeared with general grease before fitting.
The manifold steel nuts should be torqued - re-torqued to 25lbf ft.
If brass nuts are fitted I would suggest that they are torqued - retorqued to 25lbf ft also as the brass nuts are usually deeper than the steel nuts so are able to carry the same 25lbf ft loading.

[oliver90owner]

I cannot remember re-torquing any manifold bolts/nuts on anything. No high pressures (and only 14psi maximum for the induction side on naturally aspirated engines) involved, no water leakage involved and no oil leakage possible. Torqued correctly in the first place should be sufficient, IMO.