Im tired of tuning and retuning my motor to see if it performs better. I would like to buy a A/F ratio tool to help me get the optimal performance out of my motor the way it is. So which is better Colortune or a wide band O2 kit? Is the Colortune only good for getting the idle mix close and wont help while the motor is under a load? Is the O2 system worth the $160 price? I dont want to buy something that wont work but I also dont want to spend a half days pay unless I have to. Any feedback would help.

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~Nic

Wide band is best

Does it already have a narrow band O2 sensor?


If so, you can actually get fairly close with a narrow band and a digital volt meter.............

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

there is no sensor at all yet.

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~Nic

Feel'in cheap? I was when I decided trying to tune a Holley 390 was going nowhere fast over several years of farting around with no results.


With guidance from this site, a $19 three wire narrow band O2 sensor (heated - Rock Auto), $30 A/F ratio gage (local auto-parts store), a welded bung, and a little wiring, and I got the old heap running a lot better in no time. I tune idle mixture with aid of VOM under the hood, and read how she is running down the road with the gage attached to the dash.

As emsvitil said:

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Thanks. It was a good read for the O2 sensor and how it works. The only problem is Im not using a Holly carb. Mine is an Edelbrock.

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~Nic

Colortune and O2 sensor don't care what carb you are running.

Wide band O2 sensor is the best for tuning. Narrow band O2 is cheaper but can get you tuned if you spend lots more time with it.

I was refering to the web sight wjajr posted. Its had a lot of good info but it pertains to the Holly carb. I think I will spend the money and get a wide band O2 kit. Baxters auto parts has one in stock for $200. All I have to do is weld in a bung for the sensor.

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~Nic

Cheap bastard view, and additional 2 cents of blathering:

The point is a carburetor is not a precise fuel metering device like electronic fuel injection is. Carburetor air/fixture mixture is all over the place when compared to 100's of times per second self correcting spot on EFI controlled by a wide band o2 sensor. Carburetors tend run on average slightly rich if tuned correctly to prevent prolonged lean condition which can erode valves and melt pistons.

So why spend 200 bucks to read to nearest 1/100th volt representing a particular A/F ratio riding down the road when carburetor at best probably operates within 0.8v range as read by o2 sensor. Think about what happens when one opens throttle of carburetor: it goes lean for an instant, than rich once accelerator shot hits, than progresses in main jets, and on to enrichment (rich) all not controlled by o2 sensor feed back. In other words the carb is going to what it does regardless of how precise that little electronic thingy reads A/F mixture.

The point of installing o2 sensor, regardless of carburetor make and design is to get the various stages, idle to enrichment, to fall within acceptable A/F parameters that aren't stinking rich or piston head melting lean, and reasonable drivability.

emsvitil's graph is what I see when driving except the carburetor is never operating within that long nearly vertical (Ideal) portion of graph. Mixture is either in rich (.8-.9 v) or lean (.3-.2) range which as it bounces around lean to rich as throttle is moved where an average safe mixture is achieved. That long steep section of graph looks as if it would be easy to tune to run in the zone, but look at the "X" axis of graph noting that steep slope takes up a very small distance, a minuscule target for a carburetor to hit with any consistency for any length of time.

All that said, with cheap narrow band set-up one can still tune idle circuit with volt meter readings in 1/100th of a volt because at idle the load on engine could be considered constant with no throttle changes. Once throttle opens or closes while under way all you need to know is if the tide is in, is it out, or at ebb.

So, my point is why spend 200 bucks when you can get the job done for about $50 or less. That was the point of the web site I directed you to.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

It is as simple as this. I could spend a lot of time and save some money or I can spend some money and save a lot of time. I know a carb is not as precise as an EFI, that is a given. What im trying to do Is see how it is performing not only at idle but at cruseing speed as well. This is so I can "see" how the A/F is instead of trying to "feel" hoe the motor is running. I know I can do the same thing looking at the spark pulgs but again its a matter of taking the time to do so. And in my original post I said I was tired of tuning by trial and error. I thank you for all the post in how the two O2 sensors differ. Im going to buy the wideband kit and tune that way. I will post my efforts latter as it is a go on green raceing this weekend at riverdale raceway.

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~Nic

Get the O2 bung in (both wide band and narrow use 18mm x 1.5)

A 18mm x 1.5 nut works just fine. (about $1)

also get

Dorman 65220 oil pan plug (18mm x 1.5 thread, 19mm hex head) less than $5

so you can take the O2 sensor out.



borrow a narrow band from another vehicle and hook up to voltmeter and see if that's enough.

If not, get wideband.


I tuned my motorcycle (carb) with a narrowband.

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Couldn't we all. Time needed to install wide or narrow sensor & gage, and or read with digital VOM exactly the same, bung same, money different, I don't get your point.
Apples and turnips. How would one look at flame color while motoring on down the road over hill and dale? Watching flame color change as described on Colortune site as carburetor passes through various stages is mostly bunk. One would be hard pressed to get an engine in N or P on the main jets blipping throttle, and never could see what the flame looks like within combustion chamber under load, and never at enrichment stage or open vacuum secondaries; all of which can be monitored by measuring combustion byproduct with o2 sensor while under way in comfort of driver’s seat.

Been there done that, and it’s not a real handy method. Finding a quiet road where one can motor along at 45 mph for a short distance, pull over, remove hot plug, read its color, and make a calibration change to carburetor on hot engine, or run back to the garage over and over again is not too productive. This method will work for main jetting, but good luck on transition and enrichment tune.



I feel your pain.
I spent four years frigging around with a loping cam, low vacuum, and Holley’s infinite combinations of tune culminating in total frustration, and an o2 sensor.

Within a few short test drives carburetor and timing was roughed in for all driving conditions by reading dash A/F gage, and vacuum gage perched atop dash connected via six feet of vacuum hose taped into manifold vacuum source. Using both gages and tachometer one can instantly see exactly what carburetor is doing, and engine’s response while under way.

Tuning continued by making single small changes between hundreds of miles of driving. This lead to discovery that my engine/carburetor combination acts like two different engines between 500 to 3000 rpm and 3000 to 6000 rpm due to a lot of cam event overlap. Carb and engine get along much better in higher rpm range, than low rpm- low vacuum condition.

What? Green racing; do tell.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

.................... im drunk so I wont relpy to all your comments. But go on green is a drag race where the tree is like a stop light. There is no yellow count down, its just red and GO!.

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~Nic

Oh! For an instant I had a vision of a bunch of goofy looking iron running on electrons and battery acid, lining up belching ozone, and the track smelling of a lightening strike. LOL

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Ok here is the update....... on a different thread. DERP

http://www.slantsix.org/forum/viewtopic ... highlight=

_________________
~Nic