Air Fuel Ratio Meter

[Graham-P]

I'm considering fitting a Alpha Weber Air Fuel Ratio Meter this one to get my very rich running carb down to a sensible setting! Do you think I need two lambda sensors and how do I wire up two?
Has anyone else fitted one or had any experience with these?

Graham

[Boosted LS1]

I use a simple edlebrock version with one lambda and a bank of led's. I assume you're using a holley? A visual inspection from a distance into the chokes may be revealing. What you don't want to see is fuel coming out of the nozzles when the engines idling. Also check the chokes are virtually closed at idle.

Boosted.

[bluesatin]

I have the same version and works fine for me off one bank- could always swap over when setup. Most useful thing I cound is the different in changing the accelerator cams and what it did to the mixture. I run a holley HP carb.

[eliot]

you can run it of one bank, I put a boss in each bank so i can move around.
That looks like a narrow band setup, you can make one yourself for a fraction of that. A narrow band gives out a 0-1V signal depending on the mixture, so all you need is a DVM or make a little LED bar-graph. You can pick up a brand-new narrow band for about £40 (or peanuts at the scrappy) and then make your own gauge following the info here:
www.ffp-motorsport.com/tuning/o2meter.php

also read a little more here:
www.telusplanet.net/public/gilesij/Volvord/carb_jet.htm

Narrowbands are OK to get an understanding of whats going on, but the cost of widebands which will readout the exact air fuel ratio are much cheaper now - if youre thinking of spending that amount of money - GET A WIDEBAND.

[Graham-P]

Hi Boosted,
I'm using a Speed Demon, I have set the carb up as per the DVD, the transfer slots (a small square) are visible just below the bottom edge of the butterflies and there's no fuel from the venturi boosters on tick over and the fuel bowl level is about half way up the inspection windows. I think the problem area is the mixture screws and idle screws, it's almost like it's either v rich or lean just can't quite get the right balance on it.

edited to say thanks guys......looks like a bit of reading is due....good job it's quiet at work at the moment!

Graham

Edited by Graham-P on Wednesday 3rd January 13:15

[steve_d]

Graham-P said:

Hi Boosted,
I'm using a Speed Demon, I have set the carb up as per the DVD, the transfer slots (a small square) are visible just below the bottom edge of the butterflies and there's no fuel from the venturi boosters on tick over and the fuel bowl level is about half way up the inspection windows. I think the problem area is the mixture screws and idle screws, it's almost like it's either v rich or lean just can't quite get the right balance on it.

edited to say thanks guys......looks like a bit of reading is due....good job it's quiet at work at the moment!

Graham

Edited by Graham-P on Wednesday 3rd January 13:15

Half up the windows is too high. Should be so that fuel just escapes when the plug is removed. So with windows I would turn the level down until you cannot see it in the window any more.

Steve

[eliot]

steve_d said:

Half up the windows is too high. Should be so that fuel just escapes when the plug is removed. So with windows I would turn the level down until you cannot see it in the window any more.
Steve

Holy moly I thought Carbs over fueled - I would of thought even half way up the footwell is too much....

[Boosted LS1]

Graham-P said:

Hi Boosted,
I'm using a Speed Demon, I have set the carb up as per the DVD, the transfer slots (a small square) are visible just below the bottom edge of the butterflies and there's no fuel from the venturi boosters on tick over and the fuel bowl level is about half way up the inspection windows. I think the problem area is the mixture screws and idle screws, it's almost like it's either v rich or lean just can't quite get the right balance on it.

edited to say thanks guys......looks like a bit of reading is due....good job it's quiet at work at the moment!

Graham

Edited by Graham-P on Wednesday 3rd January 13:15

When is it rich? Is off idle, cruise or WOT? With the holley the butterfly has to be below the top of the transfer slot so you get smooth transition from the idle circuit onto the main jets. I'd imagine the demon's the same but stick with the DVD if in doubt. Also, you probably have 4 corner idle, set them up slowly by ear and they should end up the same. For fuel level, I'd set it up at the bottom of the inspection windows.

Boosted.

[tuxman]

Graham set bowl level first then wind all screws all the way in then out 1 turn you have to adjust all the idle screws the same amount and try about 1/4 of a turn at a time ,i also found the best way was to do a adjustment then go for a little drive then see how it is ,also when you set bowl level do it at 1500 rpm that way pumps are running at 13.8 volts ,you can get a change in pump performance compared to voltage .