carb tuning with o2 sensor?
Laughing Gas
Joined: May 2006
Posts: 1,140
Likes: 13
From: Port Orchard Wa
Senior User
Joined: Dec 2014
Posts: 279
Likes: 0
From: spokane
it does seem to be pretty solid logic. I cant find any holes in it.
Laughing Gas
Joined: Aug 2000
Posts: 1,010
Likes: 65
From: Eastern, Idaho
I bought summit racings version of the AEM wideband gauge. Saves time and gas. I wired a cig lighter plug on the power side of the harness and run harness out window then keep the exhaust port plugged when i'm done.
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Cargo Master
Joined: Nov 2011
Posts: 3,354
Likes: 49
From: Great American SouthWest
Judging by your responses, this does seem to be a good idea, and Innovate seems to be the way to go.
I'll find one on sale, then I can tell the wife how much money I saved...
I'll find one on sale, then I can tell the wife how much money I saved...
Senior User
Joined: Oct 2016
Posts: 401
Likes: 3
From: Rockville, IN Temporarily
I'm going to be watching to see what you come up with Papa. I'm entertaining either a switch to a auto overdrive and a fitech system or other. I love driving my truck but the trips to gas stations needs to slow down some.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
The factory advance curve needs tuning inside the distributor, that helps quite a bit too especially vacuum advance. The Y block in my truck likes plenty of ignition timing advance over stock spec and will tolerate crappy fuel, but any motor will benefit from this. At highway cruise shoot for around 16 to 1 AFR and check for evidence of lean surge or excessive temperatures. Wide open throttle mixture around 12.5 AFR. Idle AFR doesn't matter too much, wherever it idles best but around stoich (14.7) will help it to run cooler at idle.
Laughing Gas
Joined: Aug 2012
Posts: 920
Likes: 20
From: Malheur Co. OR
A wideband can help, but can also lie. The sensor will only tell you how much O2 is in the exhaust vs atmosphere. If you have a misfire or exhaust leak before the sensor you will have extra O2 in the exhaust stream which will make it look like you have a lean mixture. It does not tell you how complete a burn you are getting. Although out of reach of most enthusiasts, a 5 gas analyzer is a much better way of adjusting a carb. These machines measure O2, CO2, NOx, CO, and hydrocarbons. If you are interested in learning more about tuning with a 5 gas, find a copy of the latest Hotrod, issue 0617 with the Shelby on the cover, and turn to the Hotrod to the Rescue section.
That being said, a wideband is way better than guessing.
That being said, a wideband is way better than guessing.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
A misfire will cause an artificial lean reading, that's one reason why it's so important that the ignition is squared away before trying to tune a carburetor. Exhaust leaks before the sensor will cause the same issue.
Plug reading is a lot more involved than most people think, can determine a lot, but it also takes a lot of experience. A wideband sensor is the way to go these days because the cost has come down so much, and most people didn't start out reading plugs. Modern gasoline doesn't "color" the way it used to either.
Plug reading is a lot more involved than most people think, can determine a lot, but it also takes a lot of experience. A wideband sensor is the way to go these days because the cost has come down so much, and most people didn't start out reading plugs. Modern gasoline doesn't "color" the way it used to either.
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Posting Guru
Joined: Jan 2005
Posts: 1,051
Likes: 0
From: Douglas, Georgia
Knowing you are rich or lean doesn't mean squat if you don't know how to change it.
If you don't have a pin vice, 10-32, 8-32, 6-32 set screws, 1-80 drill index, and the knowledge of what changing a PVCR, TSR, IAB, MAB, and emulsion restrictions does, than seeing you are off in certain places doesn't really matter.
There is more to a carburetor fuel curve than jets and idle screws.
If you don't have a pin vice, 10-32, 8-32, 6-32 set screws, 1-80 drill index, and the knowledge of what changing a PVCR, TSR, IAB, MAB, and emulsion restrictions does, than seeing you are off in certain places doesn't really matter.
There is more to a carburetor fuel curve than jets and idle screws.
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