I have the new converter installed, fixed the broken rear wheel studs, found a square 9/16" socket to fill my differential with, and installed my 02 meter. Except for the heating element not working right (I will get to it later, must be a loose connection or bad relay), it works pretty good once it gets warm.
Here is the story, and unfortunatley with the weather here I have not had the opportunity to WOT it from either a stop or a go, so no data on how the carb is working at that point. If I need to wait for that data to proceed, let me know.
At idle, hot, in drive, I am running a 14.2-14.5:1 AF, idle park 13.5:1 AF, cruising 35/40mph I am running 12:1 AF.
Thats a bit rich for my blood, and could possibly be why I am using _so_ much gas. I have "dipped" into the throttle (maybe half, maybe not), and it shows no sign of change from the 12:1 AF.
If the weather is nice tomorrow morning I will try to get a WOT (street tire...) 0-45 or 40-65 (with elec kickdown disconnected).
What part of the carb am I looking at for these rich cruise levels? It is already jetted pretty lean for the size of the cam, engine and 6500rpm operating range (I think lean jets anyway).

Thoughts? more info needed?

Matt

Those are pretty specific numbers you are coming up with, is this a wide band O2 sensor or a generic 4-wire heated version?
For WOT air/fuel readings, you would be changing the jets.

generic 4 wire heated, but the instructions come with numbers to correlate to their colors that they say are about dead on for exhaust gas temps of 800-1400*. Its the same unit my cam guy used on his dyno, but no its not a very expensive unit.
I was thinking of buying some stuff from radio shack to get a digital volt output but tapping into the sensor, but this conversion chart seems pretty good.
Do you think I am taking too much stock in this?
All I know is my carb was modded and I installed a larger cam and my mpg went from 10 to around 4, and I am trying to figure out why.. and very rich at cruise would explain part of it. I could understand a drop from 10 to 7.. but how it is now..

Matt

I would bet that the 12:1 readings are actually the limit of the sensor, and that you could be even richer than that......

During cruise;

On a holley you will be changing the main jets and or the power valve. The power valve could be getting pulled open too soon because it's too high of a value.

On a QJet, again main jet area ( rod and jet combination ) and or the power piston spring tension.

I don't know what you have basically.

Make sure you put a fresh spark plug into one of the holes before you start tuning, so that you can reference it's condition as well as relying on the meter.

Don't place much confidence on real A/F with that setup. If your MPG truly dropped that much you are much richer than 12:1. Something sounds wrong to lose that much mpg.

There's very cost effective wideband units ($350-800)out now, there is no reason for anyone doing professional tuning to use anything but one. I'm surprised a guy on the dyno would ever use a narrowband.

Based on my own experience with a 4 wire heated unit, I agree with Doug. Also, if you ever race and use leaded fuel, I think you will kill the O2 sensor.

Jim

I use a NB (narrow band) all the time to tune. But like the others mentioned it is only good to tell 14.7:1 or richer/leaner then that. It is almost impossible to use it for any accurate numbers. I use mine to set idle, and cruise. I have them set for 0.3V which is a little leaner then stoich. The car seems to like that. Any leaner and it will suge a little under light loads.

Steve

Originally posted by Epistuff:
Based on my own experience with a 4 wire heated unit, I agree with Doug. Also, if you ever race and use leaded fuel, I think you will kill the O2 sensor.

Jim I get alot of hours with my wideband sensor using race gas. Probably 75-100 hours worth of tuning, which is alot. The new wideband sensors are fairly cheap now, too.

Also, call a dyno facility and ask what they say about sensors and race gas. Usually they report that they've never had to change one yet. Kinda surprising. Many shops use a sensor setup much like the Innovative type, instead of the $2000+ units.

I don't know Matt, I bought mine form Nordskog performance and they told me not to use any lead with it (leaded fuel or octane boosters). Also see the 4th paragraph in this link where it says **Notice**
Lead and O2 sensors (http://www.knfilters.com/airfuelmonitors.htm)

Maybe the widebands are different?? BTW, Nice Camaro! I dig that crazy distributor machine also.

The sensor is an ARM1 with a heated o2 sensor. I drove around today, and it reads ok fuel level at idle, but when cruising, it is reading what equates to on their color chart about 12:1, dropping to 11.5:1.
Its a holley 750 DP with an 850 baseplate, choke horn milled, carter 172 pump, 1/2" fuel line, 8AN fuel feed, and this stuff I will just read off the chart because other than jet sizes, I don't know what the stuff is really other than the air bleeds.
HS air bleeds 28 front/back
jets 72/78
LS air bleeds 59/59
squirters 31/31
needle and seat 120 but I assume thats .120

this is with jet extentions and nitro floats, 6.5 PV. Earlier on someone said my power valve at 6.5 not correct, but then you think the problem would be very rich at idle, where I am making like next-to-no vacuum, but ok at cruise where the car pulls well over 6.5..

thoughts..?
Also, this dyno sheet from a regular dynojet has my AF ratio on it. This pull was with a stock 12" junkyard converter just to get the car home (and I suppose to dyno it while I waited for my old converter to be inspected).
I assume the dyno shop used a good 02 sensor, and the AF looks to be just about right, a bit on the rich side...
But that is under hard work for the engine.. does all that say is that my carb works fine when you romp on it and it just dumps fuel when your plopping around town?
Maybe I'll get lucky and an EFI system will fall off the back of a UPS truck.. carbs!#@*$
http://www.detroit-iron.com/images/combodyno.jpg
Matt

There's quite a bit of difference tuning WOT, and part throttle. A good shop will tune an entire fuel curve, and charge more $$.

A dyno sheet to prove your engine will make 400 (or whatever) horsepower ... doesn't have much to do with part throttle tuning.

If it were a Q'Jet I could give better ideas ... but for a Holley, you're probably looking at float / PV changes. Other than that, I don't know how the Holley meters part throttle?

Thanks, Neal

Life with lead depends on the lead content. I just looked at a chart the other day.

Depends on the sensor and fuel to. The NTK's seem to last a while depending on the variables.

The LS4U Bosch I have been told can be killed very quickly, depending on the fuel.