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Old 06-19-2018, 05:27 PM   #1
rod
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Location: Kingman, NW AZ. in the middle of the longest stretch of Route 66
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Default O2 # & idle ?

I understand most everyones O2 #s will be somewhat different due to all the variations. however there must be a # + or - where your engine will achieve best idle.
FYI, I use a Holley 600 on my 327 Chevy. not a real legal 350 hp, but close. Vegas is closed for the summer, so I am trying to get several things right.
Rod in AZ
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Old 06-19-2018, 06:00 PM   #2
Ed Wright
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Default Re: O2 # & idle ?

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Originally Posted by rod View Post
I understand most everyones O2 #s will be somewhat different due to all the variations. however there must be a # + or - where your engine will achieve best idle.
FYI, I use a Holley 600 on my 327 Chevy. not a real legal 350 hp, but close. Vegas is closed for the summer, so I am trying to get several things right.
Rod in AZ
An O2 sensor, located in the collector of a race car, normally indicates very Lean at idle idle. The added overlap of a race cam, causes the exhaust to "pulse" in & out of the collector. Pulses pulling clean air, containing oxygen will give bogus Lean numbers. I bought a 24" slip joint with a 45 Bend in it for setting my idle air/fuel ratio in the car. On an engine dyno that should not be an issue, with the exhaust system they use. Only with open headers. Should be no issue in a vehicle with full exhaust. I hope the Lean reading is what you were referring to. The open collectors are the reason you normally would not idle one in Closed Loop.
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Old 06-19-2018, 09:39 PM   #3
rod
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Default Re: O2 # & idle ?

Ed, you are correct about my idle. it is about 19 @ a warm 1100rpm, with an 8" collector. I can make an 18" extention easily. I will see what that does.
thanks Rod in AZ
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Old 06-20-2018, 05:28 PM   #4
Ed Wright
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Default Re: O2 # & idle ?

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Ed, you are correct about my idle. it is about 19 @ a warm 1100rpm, with an 8" collector. I can make an 18" extention easily. I will see what that does.
thanks Rod in AZ
Rod, I found a 3 1/2" slip-on tailpipe-looking thing at a truck stop once, that turned out on the end. I bought that, and slipped it on my collector for tuning the idle, and return road driving. my spark plugs now stay pretty much white, no matter how I have been driving it. FAST XFI ECUs, in closed loop have a mode where you just tap the L key, on a cell in the fuel table, and it will learn that cel. I just drove around the pits, and down the return road on a test night here at home, tapping the L key with mine. Saved it, smoothed the table out some, put it back into Open Loop. Has been fine.

Sounded more bad-azzed when I was driving it around too rich. LOL
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