Carb tuning with wideband gauge

[Tdubbyount]

For those of you who haven't seen this or tried it for yourself, i wanted to share my experience and experimentation. I did a lot of research before buying a kit and figured it would be the best option for tuning my new carb to its full potential. I went with AEM's digital UEGO gauge kit. As far as quality goes, I don't see how it could get any better. It comes with a Bosch UEGO (universal exhaust gas oxygen) O2 sensor, so no worries there. The gauge itself comes with black and silver bezels and both black and white faces, so you can mix and match however you want. The LED display is bright and very easy to read. And best of all, its super easy to wire in. They've already done most of the wiring for you, all you gotta do is give it power and ground, weld up the bung for your O2 sensor and turn the key. They give you plenty of wire, so it will fit almost any application.

I put this in my truck when I built the new motor, so it really was a useful tool to get it running smoothly right off the get go. No guess work needed with this thing. The engine I'm working with here is a fresh 355, mild cam, hydraulic lifter, topped by a brand new out of the box Quickfuel Black Diamond 600cfm vacuum secondary carb. I started simply by setting idle, timing, air/fuel screws to where my vac at about 20 in. at about 1500 rpm. Then i paid attention to the wideband. I had no experience with these, but its pretty self explanatory. And its really interesting to put numbers to something I've always done by sight smell and sound. What i thought was somewhat "tuned in" was actually a little off. I was running pretty rich. Around 11:1 according to the gauge. As I'm sure most of you know, fuel injected engines always run at about 14.7:1. This is because gasoline takes approximately 14.64 or so lbs of air to completely burn 1 lb of fuel, leaving no extra. You don't want to shoot for this number at idle with a carb'd engine, because once you start driving, there's no computer to richen up your mixture, so you will run very lean during regular driving. Its also ok to run a little lean up on the top end with a carb'd motor. Most of them can take it, and you're not running high R's all the time, so it will do no harm. That's where you'll find the top end power anyway. You're shooting for a good balance. Not too rich, not too lean at part throttle. That's where your engine is going to spend most of its running time. Part throttle.

So after tinkering for a while, i went for a drive, and came up with some more results. At part throttle, i was running only 11-12:1. After a more extensive break in, I was comfortable to do a little WOT tuning. With a few hours and many "short drives" later, I got it to the point where I'm slightly rich at idle (about 12.5:1), anywhere from 13-14.5:1 at part throttle both town driving and highway, and only going slightly lean at WOT (from 14.5-15.5:1). I have to say, my truck has never ran this good! A simple little gauge has turned a total carburetor newbie into a half way decent tuner

I'd say this thing is worth every dime. It lets you really keep an eye on things and lets you get closer to that lean end of the spectrum where you're going to run the best, while still being on the safe side. And like I said, its really interesting to put numbers to something like this. So, fire away with any questions, comments, or suggestions!