Are case interchangable? Could you use the internals from a 2.0 (and heads) on a 1.7 or 1.8 case without problems?

Yes.

Is any one case better than the other?

I read on one of Jakes posts that he liked useing the 1.7, not sure why.

There is one combo that won't work with just swapping parts. That is the 1.7 heads on a 1.8 or 2.0 set of cylinders. You will have to bore out the 1.7 heads to allow the larger cylinders to fit.

Bus motor cases are also useable but they have a hole machined in the case for the oil filler pipe that will require some blocking ingenuity.
Ken

So all my 2.0 parts will work on a 1.7 case with out any machining?

Yes, but have you checked the case to see if it needs a line bore?

Yes if you use the 2.0 crank, rods, cylinders, and heads.

maybe Jake likes teh 1.7 cases cause they may be less stressed

Sean's got it right. 1.7's usually aren't as beat on.

The diffrence; shoot thats easy. Some are leakers and some are squeekers. Them 1.7, as mentioned above from the great one, usually show no signs of wear on the bottom end thus only prompting a top end rebuild or upgrades. Up grade the oil pump by all costs!:beer1:

Makes sence...

my recollection was that jake said the metal composition of the 1.7 - i think - was overall better/stronger.