First, what is the square port under the 2 center ports on my 12a for? Would it be ok to block it off?

Second, would it be ok to block off the 2 coolant ports on my intake?

Third, How crucial is it that each port have the same air fuel ratio? I would like to put my injectors near each port. Due to the different sizes i assume that a different amount of air will be inhaled in each. Would it matter if i injected the same amount of fuel into each port so that the total fuel matches the total air? Or should I inject more fuel into the larger port?

Thanks.

 

WELCOME TO THE FOURM,
the square hole is for the air control valve.

and it probably would not be a good idea to block off the coolant ports because the exhaust will heat up your intake pretty good which would heat up the air going into your engine (the cooler the better).

and third what injectors are you talking about 12a's have carbs on them, you only have to make sure that they are even in each of the two primary and add more in the two secondary ports as long as it is even.

 

coolant heats the intake, block em with 20 or 21mm freee plugs

the rectangular hole under the middle ports is the air injection port, block it off if want

 

if you want to convert to FI, just go ahead and get a custom manifold for that IHMO
not hard to get one made if you keep it simple and use steel
PM me if you need help calculateing runner/plenum/tb sizing