I dropped a 92 civic engine into a 94 civic, and to be sure the alleged surging issue with the 92 engine didn't happen with it in, I replaced the intake manifold gasket and used the 94 Manifold on the 92 head/block. Now, I have 2 issues: Engine surging due to coolant lines being routed differently, and the 94 manifold isn't casted off (shut) in a spot where the 92 head has an outlet to the coolant passages. Anyone know anything about what the soot-filled port on the head is for, and why it is blocked off on one engine and not the other? They are both D16Z6's, just different years. I also am wondering if that outlet from the head would allow oil or oil pressure to leak out into the cooling system, although there are no signs like oil in the coolant, or milky dipstick. Any help on this would be appreciated!