In the 70's Chevy put a std 2bbl (Rochester GC) on truck spec'd 250 I6's and went to a progressive 2bbl (Rochester 2SE Varajet) in 79. They further modified the 2SE with electronic controls to further meet emissions. Those 250's also came with factory split dual exhaust manifolds.
The 2SE came w/a small 35mm primary bore and a much larger 46mm secondary bore.
My research classifies the 2SE similar to the Rochester B, you either like it or you don't lol....
