Besides buying every size fly guide there is how do I determine the best size for a specific fly line weight. Right now I am building a 7 wt saltwater 4 piece fly rod and am considering using recoil guides. Also can one use a spinning top for a fly rod and again how to chose a correct size top guide. Thanks for all your advice in advance.

For saltwater I would go ceramics. Just use big enough guides to pass what knots you have in the line.(ie nail knot, loop to loop) With a 7 I would say you could get away with 12,10 and then 6's out to the tip.

[www.solwaycustomcomponents.com]

Rick,
I can be of assistance but would require some further info
Rod length or blank specs
Max tippett (estimate)

Priority from high to low
Distance
Accuracy
Durability

Additional
Connection size concerns

What Scott said is likely as large as you need to go. I went oversized on a LU/9'/7wt some years ago and it doesn't offer any advantages IMO, unless you like the sound of the line slapping around in the guides. No difference in casting distance, marginally more weight, very annoying "loose" feel while casting and stripping. Stay on the smaller end, especially if your going with ceramics.

I used TiCH (or whatever chem letters) coated singlefoot wire guides, the shape of ceramics MAY be easier to pass a knot through versus the wire guides. The larger guides wire guides that I used didn't make any difference although some say they do. If I re-do this one, it'll be along the lines of the advice in the preceeding post, perhaps a size smaller just to experiment.

I would go with REC single foot recoils - #3 at a min - #4 at a max. If there is a chance you will wish to overline, I would go with #4. They are so close anyway - unless they are side by side, too close to tell the difference. Also, use a REC recoil tip-top. The tip top is where you will really see the difference in weight.
The ceramics will make the rod too willowy, for me at least.

If you need, I will throw some #' 3, 4, 5. 6 on a copy machine and mail picture to you.
Herb