Unbalanced exhaust setup

Thanks to everyone for their replies. Great information. This forum is a great example of what the internet can be when it uses its power for good instead of evil. LOL.

concours said:

"
The engagement difference is 1 mm (0.040") between the two headers.
Some of it is a myth as the balanced header flange is thinner (to make some compensation for the rings) than the non balanced so only that 1 mm difference.
The thread pitch is around 1.8 mm (per turn) so that 1 mm is not much more than a half turn extra."

I have to diasagree.

View attachment 80010

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By Jove's you should and can with the constitution.

Short rose nut, new gasket ring just seated, gap from head to rose nut.

Factory balanced header = 5 mm gap.
AN unbalanced header that has a thicker flange than the OEM = 4 mm = around one half turn more engagement.
Factory unbalanced header = 3 mm = around one turn more engagement.

So with factory parts there is around one turn more engagement based on the around 1.8 mm pitch thread.

I was surprised when I fit a new AN header out of the bag and found only 1 mm more engagement due to the flange thickness, are they all like that I do not know.
They were for a 1971 but I see now some form of partial radius at the pipe entrance (for a spherical seat perhaps)

I do not use the normal devices for holding the pipes to the cylinder head. My 2 into 1 exhaust is held to stubs which are screwed into the head against a heat resistant sealing ring,using slip joints and springs. With the normal set-up, the flexibility of the rear exhaust pipe mounts can affect the pressures the pipe makes on the fitting to the head. Especially if the motor is not rigidly mounted in the frame.