Sponsored Links (Register now to hide all advertisements)
It can take a little defective work to get the correct carb jets dial in. I'd start with what people are recommending for your cubic inches and go from there. I was a smog tech for 30-years and basically worked on computer-controlled feedback carbs. But you can do the same A/F testing with an O2 sensor on non-computerized carbs, then you can really get it dialed in to see how rich or lean you are at. Most people never do this; they just pop the carbs on and they run them with whatever jets they have. They might be close enough to run that way, but they could be so much better dialed in. I would look up some vehicles on YouTube and see how the people tuned them using a 02 meter. It will cost you a little bit for the sensor and gauge, but you will be able to see exactly what your A/F ratio is at idle, driving and acceleration.
You also have to dial them in at idle, that is completely different than jetting the carbs. You want the idle A/F mixture screws turned out exactly the same amount, so both carbs are flowing exactly the same amount of fuel at idle, and both carbs' butterflies are opened up exactly the same amount. It's very important that both carbs are adjusted the same amount at idle. You can verify the idle mixture reading with your A/F mixture gauge. It can be done without the gauge but if you really want to be dead on correct and you don't have the experience of jetting carbs the A/F gauge will be a great help.
Here's a video. There are a bunch of them on YouTube, some better than others. You need a hole in the exhaust as close to the engine as possible for the sensor. I used to do this for a living then I had a stroke. Now I have a bunch of my own cars to do this to, just don't feel like it yet.
https://www.youtube.com/watch?v=D918ukEXXiU
Here is another one. This is big old Holley, but this shows you how little changes help dial the carb in and how the exhaust gauge helps you getting it correct. Lots of changes before it's finally dialed in.