There is always confusion surrounding the needle & seat on a Holley 2300, or one of the 4 barrels. Here is some explanation that may help clear up some questions.
One problem we run into is carburetors that have been re-manufactured, or customized. They may have had the float bowl switched, or perhaps the needle & seat modified.
Be careful when buying a carburetor kit. Many companies group carburetor numbers too generically and you end up with the wrong needle & seat. For example R-1850, R-1850-1, R-1850-2, R-1850-3, R-1850-4, R-1850-5, R-1850-6, R-1850-7, R-1850-8 all use the 3 piece type as in the 2nd row below.
R-1850-9 & R-1850-10 use the type of needle & seat in the 3rd row (short one).
As you can see the revision number attached to the LIST number can make a big difference.
|This solid type of needle & seat was used on some industrial and truck applications, including some governor ed carburetors. The screw head is used to adjust the needle & seat. The nut locks it in place. Adjustment is external to the float bowl.|
This needle & seat can be replaced by the 3 piece listed below as long as you also purchase the screw and nut.
|This is the 3 piece type of needle & seat. Adjustment is made by turning the nut. The screw locks it in place. There are several orifice sizes, so be sure to use the Holley recommended size. Our carburetor kits are designed to use the correct size. Adjusted from the outside of the carburetor.|
|This is a shorter needle & seat. Unlike the other 2 types, this type of needle & seat is not exposed to the outside of the float bowl. All adjustments are made prior to closing the float bowl.|