SUTuner

SUTuner replaces the old SU needle spreadsheet with a modern needle-matching and tuning tool for SU carburetors — covering all three jet families (0.090", 0.100", and 0.125") across 683 real needles. FIND Enter the diameters you want at any of 16 stations and SUTuner ranks the closest-matching needles by total deviation or least-squares fit — exactly like the classic spreadsheet, but built for your phone. TUNE Start from a needle you already have, pick a region — Idle, Low Cruise, Mid Cruise/Low Accel, Hi Cruise, Hi Accel, or the whole needle — and search Richer or Leaner. SUTuner finds real needles that shift just that region, ranked by the smallest change everywhere else. COMPARE Overlay up to 4 needles at once on diameter and flow-area charts, normalized at idle so shapes are directly comparable, or switch to raw diameters to see real idle differences. APPLICATIONS A built-in reference of 89 factory vehicle applications across Jaguar, MG, Austin-Healey, Mini, and Triumph — standard, rich, and lean needle codes, spring type, and a direct link to each needle's own data. DYNO AFR LOG Tuning on a dyno? Import your logged AFR (CSV, with vacuum, MAP, or PSI) and SUTuner plots it against the needle's own station chart with editable target bands, so you can see exactly which region is running rich or lean. Keep a separate log per needle you test and compare them side by side. SUTuner works fully offline. No accounts, no ads, no tracking, no network access of any kind — everything stays on your device.