Running Right: Carburetor Jetting Basics With Quick Fuel Technology

The carburetor is one of the oldest forms of induction for the internal combustion engine, and over the decades its basic function really hasn’t changed. The rudimentary parts of the carburetor, like the body, bowls, and floats are all still used while the gate keeper to performance remains the carburetor’s jets. Possessing an understanding of how to tune carburetor jets can take a rough running engine and turn it into a powerhouse-piece that can provide consistent performance pass after pass.

When the throttle is opened on a carburetor, the amount of fuel that flows into the main circuit is controlled by the carburetor’s jets. When you go up or down in jet size, it will either richen or lean out the fuel mixture for the entire fuel curve. By making sure your carburetor is jetted correctly, it will ensure the performance is at its peak, and the engine is running correctly at all times.

The process to jet a carburetor correctly for high-performance or racing applications uses a similar method as to how you would tune a street car, except the size of the carburetor is different. Lee Walker from Quick Fuel Technology explains how you can make sure you’ve got the right jets in your carburetor on race day.

“In racing applications with huge-lift cams, big stalls, and high rpm, a larger carburetor might be needed to get the desired level of performance. As for jetting, on a new carburetor, the first thing is to see if the jetting is even in the ballpark. If the car is street legal, take it out, hold it at 2,500 rpm or so under a steady load and pull a plug. If the car is race-only, do the same thing around the pits or on the return road. It doesn’t have to run very long as this is just a baseline. Once you pull a plug it will give you a good idea what the burn is like inside the cylinder. From there you can jet up or down until you get the desired plug color.”

How can you tell when it’s time to change your jet settings on a carburetor? There are many different ways including monitoring the car’s performance via the timeslip, installing a wideband to watch your air-to-fuel ratios, or you can pull plugs between passes to see how they look. According to Walker, using several of these methods together will provide the best overall picture to see if your jets need to be adjusted.

“Using a wideband to keep an eye on wide-open AFRs while also pulling a plug in between passes is a great combination to use for any engine. When you’re using multiple methods, it ensures accuracy and prevents against variables like track conditions and temperature. The important thing to note is to listen to what your engine is telling you, and pay as much attention to what is happening in a pass as you can.”

There is one variable you must always account for when tuning an engine and that’s weather. Knowing how to adjust your jets based on the curveballs that Mother Nature throws at you will be the difference between turning on a win light, and getting the dreaded yellow timeslip.

“Weather can affect a carburetor severely in some cases — a temperature drop in between passes can result in a couple thousandths difference on an E.T. The main thing to keep in mind is how the car performs in the test and tune passes so you have a baseline. To adjust you can use the same procedure from telling if your jetting is off to tell if the car is running richer or leaner than it should. An easy way to get ahead of the game is to keep a log book full of data from your passes. Record what the temperature was, if it was sunny or cloudy, your E.T., MPH, what jet was run, and so on. The more data you put in this log the better prepared you will be when it comes to jetting at different tracks based on weather conditions,” Walker explains.

If you want to learn more about how to jet your carburetor make sure to slide over to the Quick Fuel Technology website right here!

Article Sources

About the author

Brian Wagner

Spending his childhood at different race tracks around Ohio with his family’s 1967 Nova, Brian developed a true love for drag racing. Brian enjoys anything loud, fast, and fun.
Read My Articles

Hardcore Chevys in your Inbox.

Build your own custom newsletter with the content you love from Chevy Hardcore, directly to your inbox, absolutely FREE!

Free WordPress Themes
Chevy Hardcore NEWSLETTER - SIGN UP FREE!

We will safeguard your e-mail and only send content you request.

Chevy Hardcore - The #1 Performance Bowtie Online Magazine

chevyhardcore

We'll send you the most interesting Chevy Hardcore articles, news, car features, and videos every week.

Chevy Hardcore - The #1 Performance Bowtie Online Magazine

Chevy Hardcore NEWSLETTER - SIGN UP FREE!

We will safeguard your e-mail and only send content you request.

Chevy Hardcore - The #1 Performance Bowtie Online Magazine

chevyhardcore

Thank you for your subscription.

Subscribe to more FREE Online Magazines!

We think you might like...


streetmusclemag
Hot Rods & Muscle Cars
dragzine
Drag Racing
enginelabs
Engine Tech

Chevy Hardcore - The #1 Performance Bowtie Online Magazine

Thank you for your subscription.

Subscribe to more FREE Online Magazines!

We think you might like...

  • streetmusclemag Hot Rods & Muscle Cars
  • dragzine Drag Racing
  • enginelabs Engine Tech

Chevy Hardcore - The #1 Performance Bowtie Online Magazine

chevyhardcore

Thank you for your subscription.

Thank you for your subscription.

Chevy Hardcore - The #1 Performance Bowtie Online Magazine

Thank you for your subscription.

Thank you for your subscription.

Loading