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Carter Metering Jets 120-27
Carter Metering Jets 120-27

Carter Metering Jets 120-27

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Your Price: $5.25
Carter AFB carburetor metering jet. Select your correct size.
Part Number: 120-27
Availability: In Stock

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Carter carburetor metering jet. Price is for 1 jet.

To determine if your main jets are correct you will need to look at your spark plugs. A dark, or black plug indicates a rich condition. A light, or white color indicates a too lean condition. Move up, or down one size at a time, then drive the vehicle at a sustained speed for 20 minutes. Start the test over until you get dialed in. This is important so that you don't ruin your engine.

Most AFB & AVS carburetors will have matching jets in the primary and then matching jets in the secondary. The Weber marine, 4 barrel is an exception to this. The jets can be a different size one each side of the carburetor.

To compensate for higher altitude, change your jet .002 for over 5,000 feet. This is approximate because with the lousy fuel we have these days, the old ways of calculating sizes just aren't the same anymore. Using the testing method above is the best way to be sure.Carter used a 3 number system when marking jets. When the 1st number is 3, then the jet size is less than .100 inch. 365 would mean .065. When the 1st number is 4, then the jet size is .100 inch or more. 410 would mean .110.Jet sizes on the Carter carburetor can sometimes be hard if not impossible to read. In those cases use drill bits to measure the hole, then convert the drill bit to decimal.

Main metering jets for the Carter carburetor. Price is for 1 jet.

AVS - short jet. Some of the AVS carbs use the longer jet.
BBD - short jet. Some of the early BBD carbs used a long jet 1/2" or so.

WD-0 - no gasket needed
Some Carter jets use a 3 digit number to indicate the size. Example 630 would = .063 in our list.

Jet Testing

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.

WCFB Jet Sizes

Jet size: 5/16 x 24

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