Holley help needed

[bigblock73]

Can anyone tell me the difference between a 4150 and 4160 series carb? I have a 3310 and want to add a rear metering block kit. Anyone here have the same carb, or add the rear block kit?

[Robertjust777]

When it comes to Holleys, 4150 and 4160 refer to the two most popular models of Holley carbs. A 4150 has both primary and secondary metering blocks, allowing you to change jetting for both the primary and secondary circuits. The 4160 models utilize a metering plate in the secondary , which has fixed, non-adjustable, metering orifices. All 4160 models have vacuum actuated secondary throttle plates. The 4150 models come in either dual mechanical throttle plates or with vacuum secondaries. All 4150's have dual accelerator pumps, and dual fuel inlets hence the term "double pumper." The difference between vacuum and mechanical secondaries is simply in how the carb actuates the secondary metering system. In vacuum actuated carbs, the secondaries open up only when the vacuum across the primary venturis reaches a certain level. A diaphragm housing on the side of the carb contains a changeable spring which controls precisely when the secondaries open. On a mechanical secondary carb the secondaries open when the throttle lever reaches a certain position. The simplest way to tell which type you have is to look down the throat of the carb, with the engine off, and pull back on the throttle lever. If the secondaries open, its a mechanical secondary.

and about being interchangable im not sure. correct me if im wrong though

[prostreetC-10]

Originally Posted by robertjust777

the 4150 models come in either dual mechanical throttle plates or with vacuum secondaries. All 4150's have dual accelerator pumps, and dual fuel inlets hence the term "double pumper."

huh??? Not correct but I know what you were trying to say!

[bigblock73]

Thank you man!

I know I have vacuum secondaries, and a metering plate in back instead of a block...so I must have a 4160 series carb then? If so, I should be able to buy the kit Holley sells to convert the plate to a block. Sound accurate?

What had me confused was I was going by the model number of carb I have (3310), and assuming it was completely different than a 4150 or 4160, which as you said, must just be a series.

[Captainfab]

The original 3310-1 Holley was a 4150 series carb and was rated at 780 cfm. The rest of the 3310's the 3310-2 and up were all 4160 series carbs and rated at 750 cfm. The number 3310 is the model number of the carb and is always stamped on the choke horn of the carb.