Are you turning the carbs upside down to adjust the floats? That is on the SU video from ztherapy but it doesn't work with the valves you buy nowadays. They were using Grose valves in that video. Those are built different and would not hold the weight of the floats while setting the gap between the float and the lid of the float chamber. The newer needle valves will not hold the floats up. I fought with this for a long time then made my own "float chamber" out of a clear glass jar and set them that way. That's been about 10 years ago and I haven't had to touch them since. They run great. I got rid of the lid with long ears and use two short ear lids essentially turning them from 3 screw carbs '71-'72 to early four screw carbs '70-'71.

Edited 4 hours ago4 hr by siteunseen

9 hours ago, emptech said:

I like the idea of using a brass screw, either off the shelf or fabricated. I have a lathe, so I can fabricate the screws. What did the screws end up weighing?

Last time I messed with this, I tried to use off the shelf screws and I could not get enough mass packed into a small enough package. I've found that 4 grams is a good amount of mass to get the float to sit level at equilibrium, and the wood screw just didn't weigh enough.

Here's a failed attempt to use a brass wood screw instead of making my own weights from scratch. Pic of a wood screw chucked up in the lathe, narrowing the head, The process of narrowing the head worked fine, but the amount of mass remaining wasn't enough. I ended up making another pair of weights from scratch.

Here's a pic of what didn't work out: