Bob Martin wrote:

Pushrod tube? As in the throttle linkage or something?

Nothing to do with the carb. Each cylinder has two valves (intake and exhaust). These
are opened by a camshaft, which is located in the center of the engine. The camshaft
lobes push indirectly on rods that run up to the top of the cylinder to activate the
valves. Each rod is encased in a tube about 3/4" in
diameter. On Lycomings, these pushrod tubes are located above the cylinders.

George Patterson
This marriage is off to a shaky start. The groom just asked the band to
play "Your cheatin' heart", and the bride just requested "Don't come home
a'drinkin' with lovin' on your mind".