Hi can anyone help me identify which carb I have on a 4btt which I am breaking in after having a new piston and sleeve installed ( not by me ). I heard that there are a couple of different carbs that it may be. One is harder to tune than another. I am having some problems trying to tune it ( could be me too as I am new to tuning ), but I did notice that the low speed seems to be in excessively compared to another engine I have. It is in at least 1.5mm from flush and still seems rich? I cannot get a good idle and has started stalling a lot. This is after I followed the second break in procedure. I believe I have the idle gap correct as well.