how do you install a catch can on a 93 fd w twins,
 

i want to install a catch can, and eliminate the pvc valve like the 95 model is set up, but all the diagrams i have found are pretty confusing! thanks guys!

Yes!

i just wanted to know if i can use a vented, or non vented can when you run it off of the turbo elbow.

You can use a vented can and vent it to atmosphere, or you can use an unvented can and either vent it back into the UIM via the PCV or back into the intake track via the nipple on the primary intake elbow.

Can I run this off both oil filler neck nipples like so? Follow green line (note Tee connector). I would run it off the lower filler neck directly, but its harder to access than the it lower counterpart by the intake elbow. Is this setup OK? Yellow will be a vent filter.

http://i175.photobucket.com/albums/w...photo-35-1.jpg
http://i175.photobucket.com/albums/w...photo-36-1.jpg

If you are using a breather, you have no need to route anything to the intake elbow. All you need to do is to run ONE line from the oil filler neck (and cap the other nipple) to the catch can. If you are running a breather, then that's all you need to do. If you aren't running a breather, you run a line back to the intake elbow for the vent.

In my diagram, nothing is routed to the elbow itself. It is merely a second source of oil to the can. Is that OK? Does the hard pipe near the primary highlight in green connect directly to the lower oil filler neck nipple.

Ok, then where is the left side of that Y split going for your green line?

You can see in the second picture, it goes to the hardpipe (which I *THINK* routes back to the filler neck).

https://i175.photobucket.com/albums/...photo-36-1.jpg

The green in this ^^ picture (that I would like to route to the T connection in the first picture) is the same hardpipe connection as the right side connection of the OP's picture here:

https://www.rx7club.com/attachment.p...5&d=1204365524

That hardpipe routes from the "downward" nipple on the filler neck to connect the intake elbow. If you are venting the catch can, there is no need to use that line. Instead of the downward nipple on the filler neck going to that hardpipe and then over to the intake elbow, you just route it straight to the catch can and vent it. Then just plug the nipple on the intake elbow.

How do you access the lower oil neck nipple? I couldn't get to it, so I thought of this setup. Is there any inherent issue with it? Siphoning issues perhaps?

I've never really had a problem accessing it, but it's been a while since my car was closer to a stock setup. You could remove the filler neck for the oil to do it.

If you cannot access the line at the filler neck, just cap off the nipple going to the UIM and then take the line coming off the hardline by the waterpump and run it to the catch tank (with the vent). Then cap off the intake elbow nipple.

I'll give it a try. Thanks.