GN7 is correct. a 4777-4 is a model 4150 double pump. I think the confusion here is the difference between metering blocks (adjustable jets) and metering plates (non adjustable) like on a 4160 carb. Your carb has metering blocks on the secondaries. Factory jets are 67 primary, 73 secondary with a 6.5" power valve on the primary and none on the secondary. The only difference from an assembly diagram standpoint, between the primary and secondary, is the lack of a power valve, the necessary vacuum port to run said power valve, and the lack of idle mixture screws on the secondaries.