[Bmcu] surface TR3 exhaust manifold?

[Mark J Bradakis]

If the mounting faces are badly warped then you may have problems
getting a good seal.  Deciding just how bad is bad is really a matter
of experience, I guess.  Do you have a decent straightedge to
check?  Usually I use a Scotchbrite pad in a die grinder to
clean up the mounting faces of exhaust manifolds before
putting them on a car.  Often that is sufficient prep work.

Using decent gaskets will help seal as well.  Moss Motors offers
what they call a High Performance gasket made of a fibrous
composite material, which sell for something like $35 per pair,
Moss number 695-070.

For about twice as much one can get a set of compacted
graphite gaskets from Uncle Jack Drews, a well known
fellow in Triumph vintage racing circles. These are
probably overkill for a street car, but they do work.

mjb.