Carter Thermoquads ~ 'More General Information'

4972 71 340 MT (3512820) 3074 3125 655 1-3/8 6
4973 71 340 AT (3512821) 3074 3125 655 1-3/8 6
6138 72 340 MT F (3614122) 4095 5137 1940 1-3/8 1
6139 72 340 AT F (3614123) 4095 5137 1940 1-3/8 1
6144 72 340 AT Export 4095 5137 1950 1-3/8 1
6318 73 340 MT F (3698327) 4098 5137 1962 1-3/8 1
6319 73 340 AT F (3698328) 4098 5137 1966 1-3/8 1
6339 73 340 MT CA (3698339) 4098 5137 1962 1-1/2 1
6340 73 340 AT CA (3698340) 4098 5137 1966 1-1/2 1

interesting specs, just realized
1971 340 had 74 primary/125 secondary jets
1972-73 340 had 95-98 primary/137 secondary jets

ask yourself why would the same motor have a 21-24 sizes bigger primary main jet, and a 22 sizes larger secondary jet, in the 72-up 340 ?? it's just not something we do when tuning a motor for the street, or at the track. it had to be because there is so much more air bleed/emulsion in the later 72-up carbs, they covered it with more jet. not only are the air bleeds 2x bigger in the same places, there's that huge air bleed in the nose of the 72-up primary nozzles, that does not even exist on the pre-72 carbs