I have an exhaust leak, I spent way to long trying to figure out where from. It seems it is coming from the rectangular port under the primary ports. Intake manifold and block are series 4. Why is this not being entirely covered by the lower intake manifold? It has a half inch or more that is not covered by the LIM and I just cannot figure out why.

 

from 81-85 and 89-2003 (also 86-88 turbo) mazda uses that rectangular port for the air pump air injection to the exhaust ports.

the 86-88 NA engines inject the air pump air thru the two end irons.

a correct 86-88 NA center iron has a round freeze plug on the center iron

since you have the rectangle port, that center iron isn't the right one.

plan A would be to plug it

plan B you can switch to an S5 lower intake, which will cover that hole. if you're still running emissions, the s4 ACV bolts on the S5 intake, and you may have to move a vacuum line, but i don't see why it wouldn't work

 

The center iron does not have an EGR hole is that a trait of S5?