Manifold Replacement

[Bob Bidonde]

There are two joints in the exhaust system. The first joint is the connection of the exhaust-intake manifolds to the engine. This connection uses studs in the block, a metal clad gasket, steel gland rings, special washers and steel nuts.
Noteworthy are the special washers. They are cup (concave) washers, and when installed the cup side goes against the manifolds. The cup washer behaves like a spring to cope with thermal expansion of the studs. Preloading the cup washers takes up the stud expansion that would otherwise loosen the connections. I torque the nuts to 35 lbs-ft at room temperature and tighten them more if there are exhaust leaks wen the engine is hot.
The second joint is the connection of the muffler assembly to the exhaust manifold. This is where some folks use brass nuts so they will not stick to the steel clamp bolts. However, many use carbon steel nuts or stainless steel nuts in this application.