AFR readings not ideal?
#2347555
08/02/17 11:06 PM
08/02/17 11:06 PM
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Joined: Jul 2007
Posts: 461 Detroit Michigan
stinger
OP
mopar
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OP
mopar
Joined: Jul 2007
Posts: 461
Detroit Michigan
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So my set up seems to like a AFR reading at 11.0 at idle. runs great,plugs are 3 years old and show a greyish tan color. has a Lunati 703 cam and timming is 19 initial and comes in fast,total is 36*. all this on a warmed up 440. question is anyone else have a set up that seems to like a fat idle? maybe a novice question but the thought crossed my mind.
Last edited by stinger; 08/02/17 11:07 PM.
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Re: AFR readings not ideal?
[Re: stinger]
#2347624
08/03/17 12:11 AM
08/03/17 12:11 AM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
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Posts: 36,041
Lincoln Nebraska
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sounds like a legitemate question to me (I dont have an ans tho). I have yet to get my innovate LM1 hooked up.
live every 24 hour block of time like it's your last day on earth
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Re: AFR readings not ideal?
[Re: GoodysGotaCuda]
#2347643
08/03/17 12:28 AM
08/03/17 12:28 AM
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Joined: Jul 2007
Posts: 461 Detroit Michigan
stinger
OP
mopar
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OP
mopar
Joined: Jul 2007
Posts: 461
Detroit Michigan
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That's a bit rich for idle, i assume that is fully warmed up?
When was the last time you calibrated the o2? I agree but it runs good. when I lean it up to 12.5 it stumbles a bit off idle. car is not stinky but gas mileage is poor. running a 950 preform carb. I don't know anything about calibrating the co2? I fully expect the poor gas mileage. maybe larger IFR's to lean it out? Forgive me I'm not worthy LOL.
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Re: AFR readings not ideal?
[Re: stinger]
#2347647
08/03/17 12:31 AM
08/03/17 12:31 AM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
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Lincoln Nebraska
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car is not stinky but gas mileage is poor. any possibility there's a vac leak?
live every 24 hour block of time like it's your last day on earth
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Re: AFR readings not ideal?
[Re: RapidRobert]
#2347660
08/03/17 12:58 AM
08/03/17 12:58 AM
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Joined: Jul 2007
Posts: 461 Detroit Michigan
stinger
OP
mopar
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OP
mopar
Joined: Jul 2007
Posts: 461
Detroit Michigan
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car is not stinky but gas mileage is poor. any possibility there's a vac leak? don't think so purs in gear at 700 rpm. idle screw adjustments are very responsive,1/8th turns makes a big difference. I'm thinking larger IFR's and maybe some larger squiters.? last time I checked vac was a steady 15.
Last edited by stinger; 08/03/17 12:59 AM.
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Re: AFR readings not ideal?
[Re: stinger]
#2347661
08/03/17 12:59 AM
08/03/17 12:59 AM
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Joined: Jan 2003
Posts: 12,144 Benton, IL.
DaveRS23
Special needs idiot
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Special needs idiot
Joined: Jan 2003
Posts: 12,144
Benton, IL.
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How bumpy is the idle? The bumpier the idle, the wilder the idle ratios are likely to be. And the more lead the timing will want. If there is much lope at idle, then I would shoot for more timing at idle. Something like 25* +/-. How did you arrive at 36* total as optimum on your combo? Low 30*s is more typical. And unless you cruise on the idle circuit (which is possible) other circuits have a much larger impact on the cruise mix, which impacts the economy. Are you using the vacuum advance? Are you adjusting for the best idle or are you adjusting to cover up the off idle stumble? Don't use the idle mixture screws to address an off idle stumble or hesitation. I would adjust for the best idle you can get, don't worry about the A/F, and if the mix screws are in the 1 1/2 turn range, then you probably don't need to mess with the orifices or bleeds.
Master, again and still
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Re: AFR readings not ideal?
[Re: stinger]
#2347668
08/03/17 01:09 AM
08/03/17 01:09 AM
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Joined: Sep 2014
Posts: 4,457 Washington
madscientist
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master
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Washington
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That's a bit rich for idle, i assume that is fully warmed up?
When was the last time you calibrated the o2? I agree but it runs good. when I lean it up to 12.5 it stumbles a bit off idle. car is not stinky but gas mileage is poor. running a 950 preform carb. I don't know anything about calibrating the co2? I fully expect the poor gas mileage. maybe larger IFR's to lean it out? Forgive me I'm not worthy LOL. If you want it leaner, you want a smaller IFR, or a bigger IAB. A bigger IFR will make it richer.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: AFR readings not ideal?
[Re: stinger]
#2347694
08/03/17 02:54 AM
08/03/17 02:54 AM
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Joined: Aug 2003
Posts: 43,218 Bend,OR USA
Cab_Burge
I Win
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I Win
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Posts: 43,218
Bend,OR USA
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What brand O2 system and where did you locate the sensor? My pump gas car liked 14.3 AFR or leaner at idle warmed up to 160F+, it drove well with 14.3 to 15.3 AFR at light part throttle cruise up to 2300 RPM I did have it below 12.8 AFR at idle and part throttle cruise and it blacked out and fouled the plugs That was on pump gas with 91 octane, 518 C.I. low deck stroker motor with 440 six pack carbs on a low deck Eddy 383 OEM style six pack intake manifold. I have learned to use my tuning tools to make me happy and not always use what is in print somewhere I don't know about and or trust The spark plugs and time slip are good measuring tools
Last edited by Cab_Burge; 08/03/17 02:55 AM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: AFR readings not ideal?
[Re: stinger]
#2347879
08/03/17 02:17 PM
08/03/17 02:17 PM
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Joined: Aug 2011
Posts: 2,864 Pattison Texas
CSK
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master
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Pattison Texas
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sounds like you are HAVING to run it rich at idle to cover up a lean tip in issue, may need a more aggressive accelerator pump cam, like the brown one,mine did,, lean it out at idle & try it, may need larger squirter.
1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5
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Re: AFR readings not ideal?
[Re: stinger]
#2347905
08/03/17 02:58 PM
08/03/17 02:58 PM
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Joined: Aug 2011
Posts: 2,864 Pattison Texas
CSK
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master
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Pattison Texas
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A lot off good points,Thanks! I'll play with the cams and see if I can clear up the lean tip in and lean up the Idle more. Also the o2 bung is welded into the collector on the left bank so could be sucking in o2 but I doubt it. Just needs more carb tuning. Runs well for the most part with no stink,fouled plugs but poor gas mileage . Just attempting to get it better then it is if I can. If the O2 was getting air,it would indicate lean
1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5
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Re: AFR readings not ideal?
[Re: stinger]
#2348197
08/03/17 11:20 PM
08/03/17 11:20 PM
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Joined: Feb 2010
Posts: 1,645 Phila. Pa.
Mattax
top fuel
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top fuel
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Phila. Pa.
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Yes 11:1 at idle is a little rich for that cam and engine, especially if the compression is relatively decent.
That said. If the fuel has less than 14.7 stoich, which is the case with most pump 'gas', then it will need to be richer than it would with a 14.7 stoich gasoline. If you're using race gas, look at the density and stoich data.
If no choke is used, then a bit richer mix idle all the time is often what works out as best. It may get warmed up enough to idle OK, but its not the same as a truly heat soaked engine.
The AFR gage may be fooled. Misfires, reversion and even the combustion process itself can cause the WBO2 or its interpretation to be off. Yes checking other gasses can help figure out what is really going on. There were good posts by Bruce 'Shrinker' Robertson at MSV, RFS and the ol Innovate forum on how WBO2 can be misleading.
Last edited by Mattax; 08/03/17 11:22 PM.
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Re: AFR readings not ideal?
[Re: stinger]
#2348393
08/04/17 12:41 PM
08/04/17 12:41 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
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Circle Track
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Lincoln Nebraska
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I always thought you tuned for a smooth idle and more vac? that would be my thinking/goal.
live every 24 hour block of time like it's your last day on earth
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