Carbking's reply is correct in my experience.During the last few years I have run several different 4bbls on my 261 powered 37 truck.I found when the carb was mounted V-8 style, primaries foward, low speed response and idle was better than when the carb was turned 90 degrees with the primaries away from the engine.Wide open throttle performance was the same either way. I'm using a Clifford manifold, which has an open plenum design, probably less sensitive to carburator position.The AFB and Edelbrock when mounted sideways, would have a tendency cause the engine to stumble when the truck was braked, the Holly 4bbl less so.Maybe on another engine, another vehicle, the results would be different.Position the carb the way it works best for you.
Yes, the core support tension springs go on the bottom.
