Wide band o2 sensor kits

[ThickCobra]

I see for carburated engines that wideband o2 sensor kits are available. You place the sensers in the same section of the side pipes as you would an EFI system. They feed the results to a provided gauge. Since they do not feed to a monitored system, you manually adjust the carburetor by changing springs and jets, etc to the desired results thru trial and error .

Has anyone tried these with success.

[mike223]

Yes - I found a wideband AEM gauge to be very helpful.

I think a logging system (Innovate LM2, or similar) may make it easier - but you can definitely pull it off with a gauge that functions well and attention to detail.


Here is the guidance I followed (I think he was using an Innovate LM2): https://www.ffcars.com/threads/carb-tuning-101.273476/



Good Luck,

Mike

[CraigS]

I have an old LM1 and it is really a great unit so I am sure the newer versions are even better. One advice I have is to spend the extra on an RPM sensor. Some of the normal driving type diagnosis can be done live by just watching the display and making notes on a tablet. But once you start working on more throttle it's better to watch the road and record it for play back. That is where having an rpm line on the graph really helps. What I found out is that too lean is usually noticeable because of a misfire but you can be way rich and never feel it.This is an example of a curve I got.
session 6 by craig stuard, on Flickr
I think this is a full throttle blast in 3rd gear. 2nd gear happened too fast but 3rd gets you up to over the limit so you need to pick your spots carefully. The spikes on either end represent mashing the pedal on the left and letting off on the right. I did it that way on purpose so I'd have reference points. You can see that maybe the left half of the curve is pretty good but beyond 7 seconds (the #s along the bottom) it is getting too lean for full throttle (you want AFR at about 12.5). BTW your link is exactly what I followed.

[mike223]

What I found out is that too lean is usually noticeable because of a misfire but you can be way rich and never feel it.

+1.

[NAZ]

I have a high-quality portable unit with two circuits I can use with most any vehicle. And in my race car I have a system set-up with an AFR gauge on the dash that I watch closer than the shift light. I also have a TPS on the carb and a recorder that provides data on every run. It is way easier and more precise to tune a carb with an AFR than the old spark plug method and most reading this really don't know how to read plugs as it's a lost art. But that said, I still use plug readings as a separate data point on AFR and also for timing and detonation indication (you can't hear detonation with open exhaust and solid motor mounts) as plugs will show things that an AFR gauge won't.

My O2 sensors are also connected to my nitrous oxide controller so I can set the AFR target and the controller will trim fuel and or nitrous to maintain that target during a run. And the controller will shut off the nitrous system if the AFR gets outside pre-set limits. So for me, an AFR monitoring system is a primary component of my fuel management system and first line tuning tool.

[Avalanche325]

The required sensor location can be different. EFI tends to use narrowband (lean, stoic, rich reading), and often need to be close to the head. Wideband, tends to be further from the head. This gives you Lambda (a real fuel / air ratio).

With just a gauge, you could get it done. But you might find you need a passenger watching. Full throttle in 3rd gear all the way to redline isn't the best time to be looking for a specific number on a gauge.

I have a Zeitronix ZT-2. You can hook up several other sensors. I have RPM. It has a serial (not USB) output. If they haven't upgraded that to USB, that would put me off.

Read this and understand it before you start and it will be methodical tuning rather than trial and error.
https://www.ffcars.com/threads/carb-tuning-101.273476/