TR6 question about running rich and pollution control

[cmacmillan]

Silly question possibly - any chance an incorrectly/partially (dis)connected pollution control system could make the car run rich (some hoses connected in the wrong place, and some carb vents capped off)?

 

[TR3driver]

Sure. In particular, the float bowl vents on the sides of the carbs have to be left open to the atmosphere.

 

[poolboy]

This "red" nipple is found on carbs installed in the 73 thru 76 engines that had the Anti Run-on Valve feature.
It's secondary purpose was to provide ventilation to the carb's float chamber when the engine was running at idle sppeds.
If the hoses that connect the nipples to the Carbon Canister are removed and the red nipple capped, the flow of fuel from the float chamber thru the jet will be hampered.
I can't say with any authority if it will make the engine run rich, though.
The results I've seen was fuel starvation to some degree when the engine was trying to maintain a steady idle.
....................
Running rich... I'd have to go back to some of the more traditional suspects....the float chamber needle valve, the choke mechanism, the mixture adjustment, and to a certain extent an air valve's failure to respond....those are carb related suspects that come to mind..
Then there are the ignition related components that might have some effect on producing a fairly complete combustion.