Balance pipes for updraught induction systems

[Richard Mole]

A balance pipe is seen on engines with twin carburettors and the rationale seems clear enough - to balance the pressures with a view to more uniform distribution of intake charges across the engine.

But the most commonly seen versions of the Limbach L1700 and L2000 for example, have a low slung single carburettor at the rear with a Tee piece feeding fairly long induction risers to port and to starboard. A balance pipe is used more or less at the highest point as the induction tubes turn horizontal en route to the intake ports in the heads.

Other versions of the same manufacturers engine fitted with a 'high level' carburettor do not have a balance pipe.

Does anyone know why a balance pipe is advantageous for single carburettor updraught systems for horizontally opposed engines?

As a curious aside, I have a very early production L1700 that I bought about a year ago with a low slung aft carburettor and updraught induction pipes BUT there is no balance pipe. So perhaps balance pipes were fitted part way through the long production life of these engines?

Does anyone on here know how the running of an engine with a single carburettor updraught induction system changes when a balance pipe is employed?

Does it help improve the idle, the cruise or affect the maximum power for example?

Just curious