This is the little O-ringed dowel in the front of the block head surface that aligns the head along with the rear bolt sleeves, and it also supplies oil to the head through a small orifice. Anyone got a part number or how to take one out? I milled my head and then drilled out the plug port in the head a little deeper and now it wont seal, looks like the rubber O-ring is rock hard and no longer sealing. I dont even know how to get the thing out. Im going to cross post this on the 626 board too as its the same MA 1971cc motor.