valve guide wear

Hi does anybody know how to check the exhaust valves/guides on the ca18 engine. I have just fitted a rebuilt turbo and had the exhaust valve guides replaced, skimmed the head, got the engine back together and it was smoking really badly. All i can think of is that the rings are worn or the engine repair place reamed the guides in correctly (the exhaust valves with new guides had much more play in them than the inlet valves). I have a manual for a 1200 nissan engine and the max is 0.2mm movement at the end of the valve stem, is it the same for the 1800 turbo engine?
I'm rebuilding the bottom end now, new shells and rings etc. but want to be sure it's not the head causing the smoke. Appreciate any suggestions you guys can make.

Specs for the CA18ET head are:

Intake valve-guide clearance - .0008-.0021
Exhast valve-guide clearance - .0016-.0029

OK. Now the only way to actually check this is with a finnicky ball gage, which can give you different readings every time you check it. The way I check guides is with the head clean (oil in the guides can make it feel different) and no valve seals in, I put the valve about in the guide enough so that the stem is coming out the seal side of the guide, and I give it a shake. It should have just a tiny bit of movement, but it's something you kinda get a feel for.

Also if you have a mike handy, check the size of the valves. Sometimes if the valves are worn and you put new guides in it, it'll still be too loose. Here's the specs for that:

Intake valve diameter - .2742-.2748
Exhaust valve diameter - .2734-.2740

OK now here's the other side of the story. If you just did the head, and not the bottom end, it could mean it's the rings. I've seen many times (especially on Hondas) that we'll do a valve job and nothing else, because the owner can't afford to put rings in. Well next thing ya know, it's smoking like crazy, and the machine shop gets blamed for it. 99.9% of the time, we tell them to put rings in it, and it quits. What happens is when you do the head work and valve job, you effectively raise your compression back to where it should have been. Due to wore valves and seats, it was allowing some of the pressure to escape during combustion. Now that everything is back to specs, all that pressure goes back on the already wore out rings, and it just blows them out.

As far as the specs being the same for the 1200, I'm not familiar enough with that motor to say.

Thanks for the information that's really useful. I checked the exhaust valve stems and there well within tolerance and the guides are new so it looks like the rings are worn. The turbos been rebuilt by a specialist but it did seem to have alot of side play on the rotor after the re-build but not sure if this could cause the smoke.
I had the bores measured and they showed about 5-6 thou of wear on each so i guess it would be ok to just change the rings and not a re-bore and new pistons ?. Do the oil pumps need checking or are they usually ok on these engines ?. Thanks again

Well, in my opinion, 5-6 thou is time to bore. But I've seen plenty of motors get by with this much wear, it's just a little too much for my personal preference. Usually it doesn't cost much to get it bored and honed, I would at least call around and get some prices before you make a decision. To me, there's no point in doing a job if there's a chance you might have to tear it back down in a couple months and redo it.

I always put new oil pumps in motors that I build, but I've seen people take the oil pump apart, clean it, and put it back in if there's not much wear in it. Again, my choice would be to slap a new one in it...

bad turbo will cause a lot of smoke ... when my T2 bit the dust, I could smoke out my entire neighborhood,

First off, I'd run a compression test if you can. If the compression turns out within specs, it might be your turbo.