66-69 Ball & Ball 1-1/4 2-BBL aftermarket carbs wrong?

Can anyone possibly explain why aftermarket rebuilt B&B 1-1/4 2-BBL carburetors are remanufactured without the important float bowl vent valves: they come with the vent valve assemblies gone and the vent seat in the bowl casting plugged with a lightweight stamped steel plug?

Chrysler's 1966 300/Newport/New Yorker shop manual and the follow up Master Technician Conference updates for 66, 68, and 69 all say that without the valves properly set, you'll suffer vapor lock or too rich a mixture at idle - depending on the setting being out of spec.

Could it be that the aftermarket company management teams simply cut corners without knowing what they're doing - or could it be that B&B eventually considered the valves as "too techy" and obsoleted?

Chris in NC <img src="http://forums.aaca.org/images/graemlins/crazy.gif" alt="" />