The carb rebuild instructions in the manual says –

“Prior to starting the 7.5 hp motor it is necessary
to purge or bleed the fuel system of excess air.”

It goes on to say that there’s an “early” and “later”
bleed system. The early one has a bleed valve activated
by holding the choke knob “in” while squeezing the primer
valve, and the later model activates by twisting the throttle
control to the “vent” position while squeezing the primer bulb.

My motor does not seem to have either system, but the fuel inlet
nipple on the carb has an extra barb for the bleed system, but
it’s not drilled out.

When I had the carb apart, I did note one little brass plug between
the high and low speed needles, that plugs a galley into the
fuel side of the carb diaphragm. If one removed the plug and
squeezed the primer bulb, I would think it would purge the air
out of the fuel pump…… “BUT” it would dump gas into the
motor housing, and would be a P.I.T.A. to get at the plug,
and not to drop the little bugger.

Anyone have any experience with these?
Hopefully it’s just a “once in a great while necessity” to
purge out the air.