I just did a 1.8 to 2.0 swap. The one I did was a SOHC 2.0, but the procedure and swap info is the same since the 2.0 SOHC is the same block as the DOHC - in fgact, I used DOHC parts for the swap.
The problems I encountered were that the 2.0 engine, although visually almost identical to the 1.8, shares no features: None of the accessories, accessory brackets, pulleys, belts or engine mounts would interchange, making the swap seem impossible.
You have to use the engine mounts and engine mount brackets from a 2.0 Eclipse - botht eh driver's side mopunts/bracket and the front & rear mount brackets. On mine, I used all of the accessories (alternator, power steering pump and A/C compressor) along with the accessory brackets off of a '92 2.0 DOHC Eclipse, but the pulleys from the Gallant 2.0 SOHC were retained. I used a Moroso Upper Radiator Hose Cap Adapter to mount a radiator cap into the upper hose right adjacent to the thermostat housing. Injectors, ox sensor, temp sensors, throttle body and all ECM-interface components were moved from the 1.8 SOHC onto the 2.0 SOHC. The 1.8 SOHC distributor was modified with a lower o-ring groove machined into the body so it would interface with the 2.0 SOHC head, allowing use of the same distributor for ECM interface. The 1.8 uses 2 oil pressure sensors, whereas the 2.0 only has 1, so I pulled one of the machining plugs out of the 2.0 oil filter adapter and used a pipe sleeve to adapt the 2nd oil pressure unit to the 2.0 housing.
The engine was installed with the tranny still in the chassis. It's a tight fit, and you have to remove the crankshaft pulley/harmonic balancer to get it to drop in. But it went in with no problem. A little wiggling to get the pulley back on the crank after installation. The engine fired right up and a quick check of ignition timing even showed the timing to be dead on without any need for adjustment. No leaks, drips or problems. The 2.0 has much better bottom-end torque, and overall performance is very nice. The installation, with everything hooked up and cleaned up, looks very stock.
Total effort was a couple of hours to pull the 1.8 out, 4 hours in a junkyard to pull accessories and brackets, 3 hours to dissassemble & re-assemble the 2.0 for installation of valve stem seals, oil pan gasket, rear main, head gasket, timing belts & water pump, and 6 hours to transplant all the accessories/brackets onto the 2.0 and install the engine into the car. Total cost came to about $600, which included the new water pump, engine gasket kit, new timing belts, fluids, radiator cap adapter, the 2.0 engine and a couple of cans of R12 freon to re-charge the A/C.
http://i183.photobucket.com/albums/x166/judge1971/2.0Front.jpg http://i183.photobucket.com/albums/x166/judge1971/2.0Side.jpg