[TR] Tuning TR3 SU Carbs

[William Brewer]

     My TR3A started idling very fast, about 22-2500 rpms. It had been running fine. I checked/set the float levels and checked the levels after running (the same level). I reset the needle (SM's) to make sure they were seated right and checked centering in the jet. I checked with flow with my German made flow meter. The forward carburetor airflow can't be slowed down sufficiently and it idles at about 1300 rpm's when tuning the carbs. The mixture seems to be set right at that rpms and the engine rev's very well. I've got the idle/airflow screw on the forward carb screwed out until it is not touching and the choke fast idle isn't touching the cam. I checked to make sure that the vacuum advance line hasn't backed out or anything. I visually looked at the butterfly and it appears to be closed down tight. Everything appears tightened down, so I don't see where air would be leaking in.
     I've tuned these many times without much trouble, but this one has got me stumped.
     I may spray starter fluid around the intake manifold with the engine running to see if it speeds up, which would indicate a leak.
     Any ideas?

     -Bill in Tehachapi