What is a "double-pumper" carb?

[Woodz428]

Thanks for the info Sal. I had forgotten about the center squirters. While they were several sizes made there are now only a couple, actually, I only saw on that wasn't a marine one. For Anthony, it has a single 50cc pump up front and uses a nozzle in the middle of the carb to spray both primaries and secondaries. They way they are able to do this is by making the secondaries 1:1 with the primaries, where as the double pumpers have a "progressive" secondary and need the extra pump since they do not open simultaneously with the primaries. While you could potentially operate one on the street it would be pretty twitchy. As noted they are race carbs, designed for 2-4 set ups, also notice there is no choke.
That's the 600cfm 4224. The 9776 isn't listed in my Holley catalog, although it is listed in the reference pages of parts. So it may or may not be a center squirter like the 4224.

[Ron61]

Just a note as everyone else has covered the technical issues of this. In the Jegs Catalog that I have, the Double Pumpers are listed in a separate group and it says Double Pumper on the top. Then they list the carb. numbers and sizes. The actual heading as I look at the book is " Classic Double Pumper" and it then gives all the sizes from 600 cfm through 850 cfm, in either the normal copper finish or the zinc finish. Some not in that group are double pumpers and will list the size of the primary and secondary pumps. Others will say mechanical secondaries, which aren't double pumpers.

Ron

[Excaliber]

I was previously running the 660 center squirters. When they were working you could actually FEEL the difference between them and the vacuum secondaries I currently run. They were FAST!

WHEN they were working, tough to dial in and tough to stay dialed in. I called them 'nervous' carbs on the street. They were like on or off.