[Healeys] BN2 throttles

[S and T Miller]

I would agree that the most likely cause is the butterfly's are probably not
centered and may have been tightened without the butterfly being shut fully.
Some other things to check are the return springs on the side of the carb
bodies.  Make sure there is enough tension to return the throttle.  Also check
that the connector between the two carbs is not holding one open slightly.  I
have taking a butterfly plate to a "wire wheel" to clean them up and have
found that it can deform the butterfly slightly on the edges and cause it to
not close fully.
If it is real close and you don't feel like taking them back off and feel that
they may seat themselves over time (as someone have stated), you could put on
some temp springs to pull them closed fully.

The Millers
"British Car Nuts"

1957 Austin Healey 100-6 BN4 35299

1959 Austin Healey 100-6 BN4 77219

1964 MGB 40841

1960 Austin Healey Bugeye Sprite AN5 34351

"Always drive them, but remember each drive in an antique car is a test
drive."