Can I test only one side of my exhaust with a wide band o2 guage?

[68charger440]

I'm going to put a new carb on my car and want to know if I hook up a wide bans 02 guage to one side of the exhaust at the tailpipe, will that reading work for tuning the carb?  My exhaust has an X pipe crossover, so the exhaust is getting mixed from both sides in the middle.

[cdr]

yes you can do it on one side.

[68charger440]

Thx

[justcruisin]

Some say you should use one each side. I have a wide band on one side only and plug inspections tell me all cylinders are even. Personally I cant see the benefit of one each side as each side of the engine is feed from both sides of the carb and as you say the X pipe mixes it up. A multi point EFI engine may see benefit from monitoring both sides.

[Musicman]

A multi point EFI engine may see benefit from monitoring both sides.

With any luck... one day in the not so distant future we may be able to monitor individual cylinders and make adjustments accordingly, but it is not this day.

[BSB67]

I'm going to put a new carb on my car and want to know if I hook up a wide bans 02 guage to one side of the exhaust at the tailpipe, will that reading work for tuning the carb?  My exhaust has an X pipe crossover, so the exhaust is getting mixed from both sides in the middle.

No value in checking for the possible lean miss on the other carb?  It seems to have all the symptoms

[68charger440]

I'm going to put a new carb on my car and want to know if I hook up a wide bans 02 guage to one side of the exhaust at the tailpipe, will that reading work for tuning the carb?  My exhaust has an X pipe crossover, so the exhaust is getting mixed from both sides in the middle.

No value in checking for the possible lean miss on the other carb?  It seems to have all the symptoms

I'm not sure I understand the lean miss on the other carb statement...  I have been operating under the assumption that my problems are from an overly rich condition on that 870 street avenger at idle since the plugs are wet and black.  Can you give me a little more on your line of thinking as to why it is a lean miss?

[XH29N0G]

This is a temporary wideband (tailpipe) you are using.  If not, my understanding is that closer to the engine can avoid issues with leaky exhaust systems (if exhaust goes out, air can also go in).  My understanding is that you can get the general picture from one side (that is what mine does), but you will miss any second order side to side differences or front back differences resulting from how air flows and fuel is delivered by the intake. 

I have found an A/f gauge on one side extremely useful for sorting out carburetor issues (at idle, cruise, and WOT).  I am sure 2 sides would be better, but I don't have that.

[68charger440]

This is a temporary wideband (tailpipe) you are using.  If not, my understanding is that closer to the engine can avoid issues with leaky exhaust systems (if exhaust goes out, air can also go in).  My understanding is that you can get the general picture from one side (that is what mine does), but you will miss any second order side to side differences or front back differences resulting from how air flows and fuel is delivered by the intake. 

I have found an A/f gauge on one side extremely useful for sorting out carburetor issues (at idle, cruise, and WOT).  I am sure 2 sides would be better, but I don't have that.

Well I'm not using anything right now, I'm trying to decide which way to go.  But yes what I was describing is a temporary tailpipe type of A/F gauge.  If I were a serious racer then I would weld bugs on both sides closer to the engine, but as a mostly street car with an occasional day at the track I don't think I need that.  That is the reason I started this thread, to decide which way to go.

[XH29N0G]

I also have not raced mine, but I did have a bung welded into one of the header pipes by a local shop.  It wasn't too big a deal.  I bought one of the innovate a/f gauge+sensor kit and fit the gauge into the ashtray (so I can close it when not in use -  I think I pulled the bezel off the gauge to get it to fit) and I also ran wires out to the serial cable which I hooked to the computer using a serial to USB adapter.  This lets me log the a/f as I drive and I can monitor different conditions to see what is working and what is not. 

[BSB67]

If the carb is lean, there will be a lean mixture, and it won't ignite.  Very common.  Usually misdiagnosed as too rich, because it stinks and you eyes burn at idle.  Usually the miss is distributed around to all of the cylinders, and they become black because every miss fire soaks the plug with fuel.  The longer you idle, the idle quality will deteriorate and will run like crap because the plugs get so fouled.  When you start the car and if it does not run perfectly smooth (i.e. not interruption is a smooth sound and rock steady rpm) could be a lean miss.  Probably 30% of the poor idle quality I see is due to vacuum leak, and/or lean miss.  Almost always misdiagnosed as rich because of the smell, and the fouled plugs.

The fact that it takes a long time to warm up to idle okay also indicates lean, not rich.

My neighbor's 427 Cobra I worked on last had a lean miss at idle.  Interestingly, it too had a 870 Avenger

[68charger440]

If the carb is lean, there will be a lean mixture, and it won't ignite.  Very common.  Usually misdiagnosed as too rich, because it stinks and you eyes burn at idle.  Usually the miss is distributed around to all of the cylinders, and they become black because every miss fire soaks the plug with fuel.  The longer you idle, the idle quality will deteriorate and will run like crap because the plugs get so fouled.  When you start the car and if it does not run perfectly smooth (i.e. not interruption is a smooth sound and rock steady rpm) could be a lean miss.  Probably 30% of the poor idle quality I see is due to vacuum leak, and/or lean miss.  Almost always misdiagnosed as rich because of the smell, and the fouled plugs.

The fact that it takes a long time to warm up to idle okay also indicates lean, not rich.

My neighbor's 427 Cobra I worked on last had a lean miss at idle.  Interestingly, it too had a 870 Avenger

Interesting...  that sure does sound like my symptoms!

[68charger440]

My neighbor's 427 Cobra I worked on last had a lean miss at idle.  Interestingly, it too had a 870 Avenger

Funny how the 870 Avenger keeps coming up in the conversation.  So on your neighbor's Cobra was it just a matter of opening up the mixture screws a bit or was it more complicated than that?

[BSB67]

We got the idle fair with mixture screws, but it still had a slight hesitation in transition.  He needed a larger IBR, and he could not get on board with taking apart a new carb and drilling on it.

[myk]

IBR?

[XH29N0G]

I am guessing idle feed (bleed) restrictor, so that the idle circuit is richened all over and the low speed idle dropped down with the idle mixture screws.  This would richen the cruise/transition before the main circuit came into play.  I don't know much about street avengers, but when I had one (a 670) it ran lean out of the box.  My other carbs have all been rich oob. 

[BSB67]

IBR?

IFR

[68charger440]

I threw on a carter competition afb that I had sitting on a shelf just to get something I can drive it with for now.  If I remember right that one is a 750 cfm.  A little small, but it works.  I think I will probably get a wide band afr setup and find out for sure where I stand.  I'm still not sure I want to keep the 870 street avenger anyway, but maybe the afr setup is the best first step.

[myk]

750's a fat carb for many of us.  On my 440 I'm considering a 670 or a bit smaller.  Probably not a Street Avenger though lol...

[68charger440]

750's a fat carb for many of us.  On my 440 I'm considering a 670 or a bit smaller.  Probably not a Street Avenger though lol...

Well mine may have started life as a 440, but at this point it is an over 500" stroker.  The 750 is a very noticeable step down in performance from the 870.  Its just the fouling problem that made me switch.  Other than the fouling, I actually have the street avenger dialed in really well.  No hesitation/bogs or other performance issues once it is off idle and all the way through the rpm range.

[justcruisin]

I don't think it is the CFM size that makes it foul plugs, maybe the tuneability of a particular carb. Going down in size to cure that problem is not the right way to go IMO, especially on a 500ci plus engine. I run an 830cfm on a 448 and it will idle clean all day.

[68charger440]

I don't think it is the CFM size that makes it foul plugs, maybe the tuneability of a particular carb. Going down in size to cure that problem is not the right way to go IMO, especially on a 500ci plus engine. I run an 830cfm on a 448 and it will idle clean all day.

Oh, I agree 100%.  I put on the 750 because the 870 idle circuit just will not come in line.  I have a couple of different threads the show the details of my tuning of that carb and where I think the problem is.  I am just using the 750 so I can use the car until I get it sorted out.  To say the least I am not a fan of the Street Avenger series.  Rather than screw with it too much more I will probably just get the 850 dp that Ron recommended.