I'm wondering if that sharp 90° turn just inside the manifold my be causing an eddy effect, dropping fuel out of vapor suspension. Creating a radius (grinding) on that squared off edge to create a short turn radius may improve things. Grinding a radius inside the carb body to match the one ground in the manifold would create an even longer short turn radius. Every little bit helps.
Bert's mesh idea is a proven one for diffusing airflow in mass airflow sensors, may help in this situation as well.
Last edited by Glowgeek; 03-19-2023 at 09:29 AM.