that explains it! ............and all this time i thought it was because i didn't understand ohms law.
Of course if you drive both ways it all averages out to level, so so the carb base to be level as much as possible.
When cars had torque tubes the driveline was level to the earth, and so were the carburetor flanges. Universal joints required working angles to operate best, and car makers liked lowering the driveshaft to get more floor room. They started angling engines downward and pinions upward. Carb flanges followed to keep the float bowls level. You can do anything you want, as long as your driveline working angles aren't excessive and your carb bowls are somewhat level.
It god damn surprises me it takes 25 posts before anybody Askes that question? :s First time I read it I thought he ment 1949 Merc on S-10 and with flat head. I expected more flaming when I see S-10 and flathead in same post.