I have 850 CS TQs, one with screw in jets, one with push in jets. Both have a brass tube in the rear of the carb for the air valve diaphragm hose. This brass tube has a very small hole in it, about 0.015". It severely restricts the release rate of the diaphragm & therefore how quickly the AV opens. I would think this would be limiting on a big inch engine. My understanding is these CS carbs were the very first TQs. The later production 6000 series carbs that I have seen just have a steel tube in the carb rear for the AV diaphragm, no restrictor, the restriction being a small hole [ larger than 0.015" ] in the diaphragm hose nipple. Seems odd that a performance carb has a device to restrict airflow but production model does not. I have only seen two other TQs that had the brass tube, both 9000 series. One was for an Aussie Ford. There were 5 Aussie models, 9071, 9085, 9091, 9092 & 9333, used on 302-351 engines. The 9333 has the brass tube, others have the steel un-restricted steel tube.
Has anyone done any mods on the brass tube, enlarging the hole? Did performance improve? Any info welcome.
