this is a good time to do a body lift if you have any interest... it makes getting to the exhaust manifolds SOOO much easier.

LOL. I'll bet it does. No interest here for a lift, I put my mod money in to my Vettes. That's why this is pissing me off, my TomTerra is mostly my daily ride.

There has been a lot of argument over whether or not this is an interference engine - with the general consensus being yes - but I wouldn't be terribly surprised if it isn't after all...

I don't understand why Nissan wouldn't release the correct answer to this - seems silly that they do not. All I know is MY engine has cutaways on the pistons. It's possible that the valves still could hit them, but 'normally' this is not the case. I would have to do some tests to be sure, but this seems moot since I am getting valve leakage. My guess is that Nissan uses different styles of pistons in the same engines and list it as interference to cover their butts.

So what do you think would cause the valve leaking you're seeing if not a piston collision? Poor machining/seating in the first place? Head warpage?

Good question and it's not a black and white issue. If you tore apart 100 engines, even new ones, some of them would leak in a similar manner. It's not a fail safe test but it gets you in the ballpark. At this juncture in my little project, I'd say that it has nothing to do with timing belt breaking, it's simply the normal wear and tear of 100k miles. An engine will run fine with some leakage, you lose a little compression. When the machine shop goes to regrind the valves and seats they will be able to see if the valve stems are bent at all. This will confirm that they were 'interfered' with.

By the way, if you can snap some pictures of the heads, pistons etc while you have it all apart it would be really interesting to see them.

LOL, great minds think alike! I took a few but my camera does not want to upload them at the moment. I'll try again later and post them.