Why is that a stupid question? Some things are a better idea to replace than others. When I did my ZC swap I completely rebuilt the engine, but there are several things that should be replaced while the engine is out. All of the gaskets should be replaced, head, exhaust, intake. Definately the timing belt (88 Prelude 2.0 Si), and the water pump. I think those are the main things that should be changed, but you should at least check all of the sensors, the thermostat and all of the various belts.
dont forget all of the little rubber hoses that are bitches to reach when the engine is in(smack against the firewall)...
I replace the thermostat, timing belt, and bi-passed the coolant lines that go in the intake manifold. When the motors sit in the junk yards it is comon to devolope pin holes in these lines. The timing belt I took out of the motor was good but it is recomended to change it. I've got a screaming zc swap. I am very happy with this daily driver. Have questions just ask man. It's in a 91 dx hatch Very self explanitory swap. Rob Primetimeimports
The sensor that most often needs replacing is the tps sensor on the back of the throttle body, definetly check this because it is much easier to replace with the engine out of the car.
B) i have a 1991 civic std wit a 89 jdm zc dohc all it has is a header and air intake and i am doin 15.23 in a 1/4
yeah, i am going to get the motor from hmotorsonline.com, cause they compression test the motors and do a look down, so it should be in fairly good shape
