What effect would wrapping a lightweight say 2wt rod with size D or even E thread.Does it alter the action or is it just looks.
I would say yes and yes.
The larger thread would be much bulkier and not look as nice.
The larger thread would also require more finish to make the wraps smooth and add a lot more weight. Something you don’t need on a 2 weight.
Just my 2 pennies
Brad
Agreed … you definitely don’t want to go there. Use Size A or smaller.
If it is your first rod or first time wrapping, I would get some of the thick thread and use it a bit to get the “feel” of what you are doing…THEN use the skinny stuff (size A).
Like said, the thick stuff will add a bit of weight and bulk, therefore MAYBE changing the rod a bit. It would surprise me if hardly any of us could tell the difference if blindfolded though.
Welll…JC probably maybe could! 
…lee s.
Yes and Yes is also my answer. I think you would be much happier with the overall finish is you would use the most common size A thread.
I noticed that you are in Bellingham, WA … there are enough rod wrappers to walk across in that area. I would suggest you find someone in the area to “tutor” you and do it the right way with A size thread. I haven’t found very many rodbuilders that aren’t willing to share the trade/hobby. I build for a full-time living and I will still share information with people and even help them save a few bucks on materials, blanks, etc.
Thanks for the input. It’s not my first and I kinda knew the answers I would get. Just wondered if one could tell the difference in the way the rod would feel and work.The ropelike look might be interesting.