Another possibility to the sintered bronze is to look at marine applications.

As leaks on closed-bilge boats are very undesirable:

(1) an 1/8 inch pipe fitting is screwed into the 1/8 pipe tap in the airhorn boss.
(2) a "drip loop" is formed from copper tubing.
(3) a second pipe fitting replaces the headless plug above the throttle plate.
(4) and the tubing is connected to the second fitting.

Result, fuel which drips down from gravity once the engine is turned off will end up in the drip tube, and will be pulled into the intake manifold assisting the choke in starting the engine when the engine is cranked, and vacuum is applied to the tube.

As the hole in the casting beneath the second fitting is small, the resultant "vacuum leak" is manageable with idle adjustment.

This arrangement was used on marine applications as late as the late 1960's.

Jon.

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