The seal on the sediment bulb went on nice and tight so the neoprene should be squashed pretty good. On the carb I could only tighten it where I think it keeps it from leaking. I do not know if I can get in there to make it as tight as on the bulb, but I could probably tighten it more if I really tried. I do not see any leakage.
This is the first time I have used neoprene. Always used the felt before.
Does the neoprene work both ways - real tight and just tight enough? Do you think this is OK?
Just tight enough should be fine. It only has to make a seal, there is no pressure unless you are running a fuel pump.
Only tight enough so there is no weeping.
I used neoprene seals on my gas line and made them a little tighter than was required to seal. The one at the carb side ended up getting very hard and leaking. I spoke with some fuel people at work and they recommended Viton. I don't know if it was the heat, or the seal material, but I pulled both neoprene seals and replaced them with a stack of 3 Vito o rings from Amazon and have not had the problem recurr.
I had to buy a few sizes to find one that fit just right, I will post a link to the right one later today.