Here at last from Holley are the new and improved 4160 model 4-barrel carburetors. These carburetors are equipped with Holley's all-new Tru-Set needle and seats, which have eliminated the need for external adjustments. This change allows for easier "bolt-on-and-go" performance. The floats have been factory-set for optimum fuel levels at 3 to 6 psi of fuel pressure and should never need adjustment. If you're running over 6 psi of fuel, a fuel regulator is required. These carburetors also include a new, refined appearance on their float bowls, main bodies, and vacuum secondary caps. Along with having upgraded choke caps for smoother engine warm-up and better cold drivability, these carbs are also the perfect upgrades for any ride.