Is there any difference in float level adjustment using brass floats vs the nitrophyl on the thermoquad?

that's a good question. AFAIK I have never heard of haveing to make a change from one to the other so I am assuming it would be the same. You might call "the carburetor shop" in Eldon Missouri & ask him.

Yes there is but also various years call for different set heights. Use your head rather than a certain spec if you can't find the spec for it.

Tell us what is the carb number and isnit correct for your application? What is the application?

Every single Carter TQ carb kit (gasket, seals, etc) instruction sheet I have ever seen (and I've got about 10 different ones I'm looking at right this moment) had one of the following statements:

"...All original metal float settings of 1" or 1-1/16" use 29/32" when plastic floats are used..."

OR

"...Applications with Cellular float (not brass) set 29/32..."

In general the kit instructions will show an OEM setting for a given carb model year because previously brass floats would have been used befor the nitrophyl stuff came out.

^^^ Ding ding ding I do believe we have a winna.

i have used varying float levels to fine tune thermoquads with excellent results. it all depends on your combination. don't be afraid to experiment. 1/32" can make a big difference. all part of the tuning process. just my experience. i really like thermoquads, but it took me many years and much experimentation to get the results i was after !

You know, I have been working with TQs for years as well, and maybe it's a bit embarrassing to admit, but having played with some different settings I never quite figured out how the float level (besides the obvious "too-low" - numeric setting) impacts the other circuits in the carburetor.

Case in point: if set too low, so the float is effectively sitting higher up in the body of the carb when fully assembled, the fuel level gets higher as well before the fuel flow into the bowls is stopped. This can translate to fuel dribbling out of the booster(s). But this has literally been the only thing I've noticed...so what else am I missing?

I do genuinely want to know because I love these carbs, the tech is awesome and I continue to play & learn on my 98xx series carbs here.

sorry it took so long to reply. what i learned about fine tuning the float level was learned before O2 sensors were used as they are today. after optimizing jet sizes and air door settings to my liking, i then played with squirter sizes. improvements were made, but i got to the point that one size was not enough, and the next size [in my collection] was too much. this pertains to light throttle tip in. a slight change in float height dialed it right in. remember, this was just trial and error [lots of that !] on my part on several of my combinations that worked out great for me. the time frame was way before the internet, and thermoquads were trashed every day with holleys being substituted. the gas formulations were different too, and i'm sure that had lots to do with my success. my projects have been parked since around 2006, so when i get back to them, i will have to go over the carbs again for sure. in the meantime, i have learned different techniques and have also gained other tidbits i am anxious to try on these carbs. one thing to remember though, is to make sure your adjustments are preformed in order according to the carter recommendations in their book. then, and only after you get your stock carb as good as it can be, start experimenting. only do one thing at a time so you don't get confused with many changes at once.