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Air Fuel Ratio and tuning

Printed From: The Ford Torino Page
Category: Model Specific Forum
Forum Name: General Automotive Technical Discussion
Forum Description: Technical Automotive discussion of anything not specific to mid-size Ford/Merc
Printed Date: 03-June-2023 at 4:09PM
Software Version: Web Wiz Forums 12.06 -

Topic: Air Fuel Ratio and tuning
Posted By: GranTorinoSport
Subject: Air Fuel Ratio and tuning
Date Posted: 27-May-2010 at 6:06AM
So I own an Innovate Motorsports LM-2 that has the wideband O2 sensor in it. It is very nice - gives instant readouts of your actual A/F ratio.

While that is nice and all, the real problem is what A/F Ratio do I really want?

Knowing 14.7 is stoiciometric, I also know that running at that level will cause stumbling, etc.

Car Craft in their - article cite an AF Ratio of around 13.0-13.5, and I quote:

"At light throttle opening speeds of 35 to 40 mph up to freeway cruise in Overdrive, the carburetor delivered consistent air-fuel ratios of between 13.0:1 and 13.5:1 which was close to ideal."

However, Ford Muscle had a chart in this - article that showed many different values in their article (and I quote):

From this chart, I would want to perhaps be up more toward 14.2 for cruise, perhaps a bit more (this is for my pickup with a 360, not much performance wise).

Right now, it is running about 14.2-14.4 in low-mid RPM cruise, 13.6-14.0 in higher RPM cruise (freeway speeds) and in the 12's for power (not WOT). Have not even checked WOT.

It seems to run well, I am at about 8-10 degrees BTDC on the timing.

This is an Edelbrock carb.

I have several rods, jets and springs and I have been changing them out, seeing the effect (it really does work, and it is quite cool).

Just looking for other's experience. It's nice knowing exactly what your A/F Ratio is, but knowing what to do with that is the other 75% of the battle...
file:///C:%5CDOCUME%7E1%5Csce2932%5CLOCALS%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml -

Scott Eklund


Posted By: Psquare75
Date Posted: 27-May-2010 at 6:35AM
I usually use the middle line for my vehicles. I have an AEM wideband in my Cougar. 

77 XR7 460/C6/3.00:1 *SOLD*
78 XR7 523/C6/3.5:1
79 F100 460/TKO500/3.25:1
'I also have some left over potatoes-I understand you can generate electricity from them'- Foote500

Posted By: GranTorinoSport
Date Posted: 27-May-2010 at 10:49AM
Then I certainly have some more tuning to do.

I think I'm going to step down a jet size next. I think I put larger jets in the primaries when I rebuilt the carb (and of course did not annotate it anywhere), just a guess.

Scott Eklund


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