I have had carbs sit in three directions.
Normal, where the linkage will bolt right up. Primaries fwd.
Primaries,closet to the cyl head & primaries furthest from the cyl head.
IMO,it really did not make any difference on my street car.
Maybe if I had a wide band O2 reader,I might have been able to see/read a difference.
MBHD
What he said.
