Motorcraft main jets, 1100, 1101, 2100, 2150, 4100, 4300, 4350. Priced per each. These are ordered by size .048, .058, etc. You will find the current jet number stamped on the top of the jet. Order by selecting the jet size from the drop down list. Price is per jet.
These are 5/16" on the threaded end.
Some of the older 2100 & 4100 Autolites are much smaller. Typically 1963 and older (assuming you are 100% sure you know the year of your carb.). This type of 4100 will probably have a plastic lever going to the secondary diaphragm. This type of 2100 & 4100 jet can be found here
- Made in USA
- Number Stamped on Top
Your old jet may have the size stamped on the top or side. 50f=.050, 50=.050
Motorcraft 2100 Jet Sizes
To determine if you have the correct jets in your carburetor, operate your vehicle for 20 minutes at sustained speeds. Stop and pull a plug. Gray - Good, Black - move down one jet size, White - move up one jet size. Do it all over again until you get a gray plug.
This assumes your engine and electrical system is in good running order.
Autolite 1100 Main Jet