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Carb Tuning with Narrowband O2 Sensor

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I've rebuilt, tuned and modified Holley and Holley-design carbs in various applications over the years, but have recently decided to try another tuning tool in one of my Mustangs. I recently had a full exhaust done on my Mach 1, complete with X-pipe, mated to my Patriot headers and, at the time, added a header collector with provisions for an O2 sensor, with the intent that I would add an A/F gauge later on.  Well, I've finally got around to it. I'm going to install a basic narrowband setup using a one-wire Denso oxygen sensor and a mounted AFR gauge. 

The gauge consists of ten LEDs that represents 0.1V each (since the sensor wire sends a 0-1V reading) and displays red, yellow and green lights. While the gauge itself does not display an actual number, the instructions do indicate what lights represent a stoichiometric air/fuel ratio.  I've also found what I believe to be a fairly accurate graphing of A/F ratio-to-sensor voltage for narrowband that hopefully will allow me to not only adjust the carb for idle and cruising, but WOT as well.  If the narrowband approach doesn't work well for me I can always upgrade to a wideband and change the sensor and gauge.

Has anybody else had experience with using a narrowband O2 for tuning their carburetor, and if so what were your thoughts?


1971 Coupe - 306ci (circa 1971) - 10:1/750 Holley/RPM Air Gap/Lunati camshaft (221/231@.050)/Comp roller rockerarms/Ford Racing pulleys/Ported cylinder heads/MSD ignition/Patriot Ceramic LT headers/Single Chambers/Carter fuel pump/NOS Sniper/9" diff./4.57 gears/B&M Holeshot convertor/B&M Shiftkit/B&M Z-Gate/CE subframe connectors/Jegs Sport Star rims/Lakewood traction bars/Fiberglass Ram Air hood/Electric fan/Rear seat delete/Relocated battery/Custom graphics


1972 Mach 1 - Ford 400ci/C6 trans/Quick Fuel 750 carb/Weiand Intake/Harland Sharp rockers/Performance cam/Patriot headers/CVF racing underdrive pulleys/Carter Fuel pump/Jegs Sport Star rims/4.11 gears/Spool/Traction bars/Accel distributor and ignition/Miloden 8-quart/Jones Full Boar exhaust/Hurst Pro-matic 2 shifter

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  • 2 weeks later...

Well, I tried one on a f.i. factory 99 g.t. with a add-on procharger, and it would swing back and forth on reading at all but full throttle. Get a A.E.D. wide band, more accurate, my 2 cents.

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Some time ago, I borrowed an AFR from a friend while trying to figure out and understand my Holley S/A 670 on my 351C 4V and posted a video.

Honestly, I had no idea what I was doing, but I did get the carb running pretty much spot on. Here's the link. OOPs it's TOO BIG TO UPLOAD!!

BUT, perhaps this post will help. https://7173mustangs.com/forums/topic/33799-holley-sa-670-tweaking-need-advice/?do=findComment&comment=350396

Ah, Time flies, memory fades. It was a YouTube link. For what it's worth, here it is. 


Edited by Stanglover
Found YouTube link.


 I learn something new every day!

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