Float level woes

[Tennessee Tim]

New member, so please be gentle...I tried to search to the best of my ability, but did not find answers.

I have a set of new-style "Made in Spain" IDAs for my 331 SBF. I am trying to get the float levels set properly, and I have some questions. I have fabricated the tools needed in accordance with the instructions I have found in several places. The first tool is the needle and seat gauge. As per the instructions, it is 25mm. My first quandary stems from the fact that none of my needle and seat assemblies are really close to the 25mm. Three of them are in the neighborhood of 24.5mm, and one is about 26. When I bought the carbs, I also bought two spare needle and seats, both of which are closer to 26mm. It almost seems as though there are two different types - the needle on three of them seems to be about a millimeter and a half longer than on the other three. However, I can find no markings that would seem to indicate two different parts. All 6 are 200s. Is this normal variation? This doesn't seem likely to me, since I have 6 needle and floats, with three having nearly identical measurements, and the other three having three identical, but completely different measurements. If this were simple manufacturing variations, I would expect to see more variability. At any rate, I don't see how I could possibly bring the 26mm parts down into spec, unless I eliminate the gasket entirely, and I'm pretty sure I don't want to do that.

Secondly, the tang on the floats are all embossed with "25.5". This is curious to me, as I would think that this is a measurement of some sort, or would at least have some meaning, but it does not correspond with any of the standard, widely published measurements. I am starting to become concerned that all of the measurements I have seen have been related to the old style IDAs, and perhaps the new styles require a different setup for float level. If the "25.5" were to correspond to the needle and seat height, it would make sense, since that is achievable with some tweaking with the two lengths of needle and seat I have.

Finally, given the uncertainty that I now have with setting the float level on these carbs, is there another, independent way confirm that the float level is correct? I.e., can I fill the bowls and check the actual fuel level against some criteria?

Any help with this would be greatly appreciated.

Tim