Does retarding and advancing ignition timing on the distributor affect air/fuel ratio?

Example, say ignition timing is set at 16 degrees and a/f ratio is 13.2, if I advance the timing to 18 degrees, would the air fuel get leaner or richer just by adjusting the ignition timing? And vice versa.

Running a NA setup and wanted to test different ignition timing at the track. A/F tuned to around 13.2 using wideband, but don't have it on right now and wanted to find out before hitting the track.

 

i believe that advancing your ignition timing will generally lean out your air/fuel mixture. i would just leave it where its at until you gain access to a wideband.

 

ignition timing doesn't have anything to do with your a/f ratio...........think about it you have X amount of air and fuel going into your combustion chamber, if the only thing you change is IGNITION timing, you haven't changed the amount of air or fuel going in.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JSpin &raquo;</TD></TR><TR><TD CLASS="quote">ignition timing doesn't have anything to do with your a/f ratio...........think about it you have X amount of air and fuel going into your combustion chamber, if the only thing you change is IGNITION timing, you haven't changed the amount of air or fuel going in.</TD></TR></TABLE>

*buzz* wrong answer...

Increasing Ignition Timing generally increases torque, which increases the fuel consumption at that load point...WHICH, will require more fuel to sustain a given AFR.

That's why when you are tuning, you tune the AFR, tune the timing...then yu have to go back and touch up the AFR Curve.

 

what superdave said!

 

Thank you guys for the information. I will keep it where it is until I get access to the wideband again.

 

actually both of you are right, on what you said. but who answered the question right was the first one.

ignition timing does not affect afr dirrectly, what it affects is torque not afr, the increased torque affect the afr. hahaha

no diss 2 no one just randomn nerdin


Ed-

 

i'll stand by my answer on this one

 

Ok, next time you're on the dyno jack the timing 10 degrees and watch what happens.

 

i know what you're saying, and i agree..........but for the sake of the argument, i'll agree to disagree

 

is this what you guys are saying:

if it were possible to measure a/f ratio pre-combustion, there would be no changes when the timing is adjusted.

but since we measure at the tailpipe, the readings are subject to bsfc(brake specific fuel consumption, aka, efficiency)... as well as exhaust leaks, misfiring, etc... so is that the real a/f ratio

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by danimal &raquo;</TD></TR><TR><TD CLASS="quote">is this what you guys are saying:

if it were possible to measure a/f ratio pre-combustion, there would be no changes when the timing is adjusted.

but since we measure at the tailpipe, the readings are subject to bsfc(brake specific fuel consumption, aka, efficiency)... as well as exhaust leaks, misfiring, etc... so is that the real a/f ratio </TD></TR></TABLE>

pretty much, if you could some how fire off your a/f mixture, and then rewind that same engine cycle, and simply changed the spark timing, the a/f would be the same. but for real world, superdave's got it

 

my point is that 02 sensors do not measure a/f ratio at all... they just look for oxygen.

so in theory, you had it right the first time... timing can't have an effect on a/f ratio, but as dave inferred, timing can affect the output of a motor under load.

interesting question

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JSpin &raquo;</TD></TR><TR><TD CLASS="quote">ignition timing doesn't have anything to do with your a/f ratio...........</TD></TR></TABLE>

Sure it does. You are changing when the burn starts. I.e., more or less time for the fuel to burn. If you advance ign timing, AFR will lean out. If you retard it, it will richen up.

Try it on the dyno. Pick a part of the powerband, and pull 5 degrees of timing without touching the fuel.... see what happens. The AFR isn't going to change a ton, but it *will* richen up.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dustin &raquo;</TD></TR><TR><TD CLASS="quote">

Sure it does. You are changing when the burn starts. I.e., more or less time for the fuel to burn. If you advance ign timing, AFR will lean out. If you retard it, it will richen up.

Try it on the dyno. Pick a part of the powerband, and pull 5 degrees of timing without touching the fuel.... see what happens. The AFR isn't going to change a ton, but it *will* richen up.</TD></TR></TABLE>

So it is safe to say on a NA vehicle where we usually run leaner at about 13.2 to 13.5 and I want to test the vehicle and advance the timing from 16 degrees to 18 degrees to increase the torque curve like mentioned previously on the post, the a/f will not get leaner by a ton so I will not get very lean and possibly damage the motor??? I am talking about advancing 2 degress of timing, all other settings staying the same.

Thanks for the info's.

 

peg that distributor


who gives a ****

hahaha just kidding,


Ed-

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DEMNTD1 &raquo;</TD></TR><TR><TD CLASS="quote">

So it is safe to say on a NA vehicle where we usually run leaner at about 13.2 to 13.5 and I want to test the vehicle and advance the timing from 16 degrees to 18 degrees to increase the torque curve like mentioned previously on the post, the a/f will not get leaner by a ton so I will not get very lean and possibly damage the motor??? I am talking about advancing 2 degress of timing, all other settings staying the same.

Thanks for the info's.</TD></TR></TABLE>

2 degrees of timing is not going to change the AFR enough that it would be any less "safe" than it was before.

 

here is a off the wall q....I'm having a little bit of detonation problems....but ONLY AT 3250 RPM-3500 RPM , does not matter what gear i'm in...then it goes away. timing was advanced 2 degrees, i put it back to stock, but still a little detonation...is it safe to say the tune is a little too agressive at that point, cause like u guys are saying 2 degrees really dont affect AFR that much, right?

BTW the set up is NA, done right, and i just dont feel like answering dumb qs like what injectors i'm running, or do i have carbon built up, etc.... the set up is DONE RIGHT... the tune is in question...lol

 

bump for answer