[DeTomaso] A/F Gauge- wide or narrow?

Tue Aug 2 23:26:06 EDT 2011

My starting point was the idle air bleeds.  Many erroneously think the main 
jets are the main contributors to how rich or lean your carb is when driving 
down the highway, yet, they are not.  Your main jets don't get involved into 
your throttle plate opens far enough to move off the transition circuit. 
While driving at steady speeds up to around 80MPH, many with built up motors 
barely have the throttle cracked.  You know the feeling - your driving down 
the highway at 70 mph in 5th and you barely have the gas pedal off resting. 
At this throttle position, your slow idle air bleeds are driving your 
mixture.

It was a cool exercise changing these small jets and observing the A/F shift 
to a desired point.  This exercise significantly influenced my gas mileage.

JT

----- Original Message ----- 
From: "Kirby Schrader" <kirby.schrader at gmail.com>
To: "Charles Engles" <cengles at cox.net>
Cc: <detomaso at realbig.com>
Sent: Tuesday, August 02, 2011 10:03 PM
Subject: Re: [DeTomaso] A/F Gauge- wide or narrow?

>
> Oh, wow.... that's a loaded question.
>
> My answer.... yes, in as far as you can adjust a carburetor.
> :-)
>
> With a typical Holley, you have the size of the carburetor, the jets, the 
> power valve and the accelerator pump available to adjust.
> What'd I forget?
>
> With EFI, you can adjust EVERYTHING!
>
> This can be good and this can be bad.... as Mike pointed out... you can 
> adjust and tweak forever...
>
> Be forewarned though... it takes awhile to get your head around what the 
> AFR is telling you.
> It is measuring oxygen or the lack thereof. Key point.
>
> It took me way too long to understand what AFR was telling me sometimes. 
> But then.... I'm kinda' slow at times.
>
> Just remember, it is measuring oxygen, not fuel.
>
>
>
>
> On Aug 2, 2011, at 9:51 PM, Charles Engles wrote:
>
>> Dear Kirby,
>>
>>
>>          Thanks.  I very much appreciate learning from you experience.
>>
>>          Next dumb question: IF you have your carb set up on a dyno, THEN
>> you do *benefit* from using a wide band A/F meter in real world in vivo
>> driving conditions to fine tune the carb???
>>
>>
>>
>>                          Warmest regards,  Chuck Engles
>>
>> PS: I have just started the head work on my next engine just in time to 
>> do
>> shade tree port work in 105 degree temps!!
>>
>>
>>
>> -----Original Message-----
>> From: Kirby Schrader [mailto:kirby.schrader at gmail.com]
>> Sent: Tuesday, August 02, 2011 9:45 PM
>> To: Charles Engles
>> Cc: detomaso at realbig.com
>> Subject: Re: [DeTomaso] A/F Gauge- wide or narrow?
>>
>> Chuck,
>>
>> See my highly opinionated answers below.
>>
>> Kirby
>>
>>
>> On Aug 2, 2011, at 9:23 PM, Charles Engles wrote:
>>
>>> Dear A/F Gauge Forum Experts,
>>>
>>>
>>>           PLEASE provide a dummy's guide to A/F Gauges.  I gather that
>>> they are good things, but questions persist, if you would be so kind.
>>>
>>> 1) How much do these things cost?
>> How much do you want to spend? There are various brands and various 
>> quality
>> items. What's amazing to me is how much the widebands have decreased in
>> price since 2000. They are as much as 1/5th the price. Very affordable.
>> I'm partial to the Innovate Motorsports stuff. Good quality, not cheap, 
>> but
>> works well.
>> They also have packages to make the gauge look like what every you want.
>> Digital, analog... black, chrome, etc.
>> You can also output to any other AFR meter if you want. Standard 0-5VDC
>> stuff.
>> I have an LM-2 to do the odd tuning with cars that don't have a built in
>> sensor. A friend with a CTS has borrowed it for the time being.
>> I have an LC-1 and wideband mounted permanently on both the Pantera and 
>> the
>> GT40.
>> Depending on your ECU (if you have EFI), you can use the output of the
>> LC-1/LM-2 to do the feedback for auto adjustment of AFR under cruise.
>> Definitely not for full throttle though.
>> You gotta' be close in the first place with your tuning... it can't
>> compensate for everything.
>>
>>>
>>> 2) Do you have mount a bung or fitting on your exhaust to use one of 
>>> these
>>> things?
>> Yep. With either the wideband or the narrow band, that is a requirement.
>>>
>>> 3) Are you mounting these in the dash or just temporary until all the 
>>> carb
>>> tuning is done?
>> Yes! :-)
>> I have mine mounted on the dash in both cars. True, as someone said, once
>> you have it adjusted, you shouldn't have to worry about it.
>> But it's kinda' like oil temperature....  do you want to know or not?
>>
>>>
>>> 4) So...you have it installed and you drive around noting that it is too
>>> lean; in the sweet spot; or too rich and adjust the carb appropriately
>> until
>>> it *always* stays in the sweet green zone?   Then, it isn't needed any
>> more
>>> or is it??
>> See above. But yeah... you can tell your ECU to log to a file while you 
>> go
>> to work and back.
>> Get home, sit quietly with a glass of wine and review whether you have 
>> any
>> 'holes' or not and fix them.
>> Like Gary said though... usually you know already that there is a problem 
>> at
>> a certain rpm. You just confirm it and fix it.
>>
>> Since I put the ancient Haltech on my Pantera in 2000 (which went up in
>> smoke, literally, a few days ago), I've learned a lot.
>> You _can_ adjust things yourself and I've done it, but it is much easier 
>> and
>> less time consuming doing it on a dyno.
>> Just depends... you can tweak either an EFI system or a carb for a long
>> time.... just depends on how keen you are.
>>
>>>
>>>
>>>          I just figured out what the tach was used for, so help me with
>>> this.
>>>
>>>
>>>                  Mr. Dummy, Chuck Engles
>>>
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