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Re: Tuning...a/f readings
[Re: can.al]
#2096189
06/22/16 12:47 PM
06/22/16 12:47 PM
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Joined: Oct 2003
Posts: 7,506
Az
Crizila
master
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master
Joined: Oct 2003
Posts: 7,506
Az
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That's actually not bad. Did you have a vacuum gage on it to see if you were in to the PV? Were you driving it under load? You could also try a little larger hi speed air bleed if yours are adjustable.
Fastest 300
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Re: Tuning...a/f readings
[Re: can.al]
#2096222
06/22/16 02:03 PM
06/22/16 02:03 PM
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Joined: Jul 2004
Posts: 19,317
State of confusion
Thumperdart
I Live Here
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I Live Here
Joined: Jul 2004
Posts: 19,317
State of confusion
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You could be seeing the opening point of the p/v or you`re on the primary jets pulling through the boosters.....either way looks good accordingly.....
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: Tuning...a/f readings
[Re: can.al]
#2096266
06/22/16 03:30 PM
06/22/16 03:30 PM
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Joined: Oct 2003
Posts: 7,506
Az
Crizila
master
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master
Joined: Oct 2003
Posts: 7,506
Az
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Follow the little tuning booklet that came with that carb - in particular the graph.
Fastest 300
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Re: Tuning...a/f readings
[Re: can.al]
#2096280
06/22/16 03:40 PM
06/22/16 03:40 PM
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Joined: Aug 2003
Posts: 43,173
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,173
Bend,OR USA
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I like to see 14.8 to 15.8 AFR on idle and part throttle cruise at engine operating temps, not on start up  To lean out the main circuit at or above 2500 RPM try enlarging the bottom step on the primary rods, both sides  Leave the part throttle step the same size, if you can 
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Tuning...a/f readings
[Re: can.al]
#2096287
06/22/16 03:54 PM
06/22/16 03:54 PM
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Joined: Jul 2004
Posts: 19,317
State of confusion
Thumperdart
I Live Here
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I Live Here
Joined: Jul 2004
Posts: 19,317
State of confusion
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1405 edelbrock (600 cfm man. choke)
think i'll try a lighter step up spring...maybe lower vacuum at higher speed
is pulling the metering rods into the power circuit a bit early? OOPS............LOL
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: Tuning...a/f readings
[Re: can.al]
#2096316
06/22/16 05:00 PM
06/22/16 05:00 PM
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Joined: Feb 2014
Posts: 1,707
central il.
second 70
top fuel
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top fuel
Joined: Feb 2014
Posts: 1,707
central il.
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Check your vacuum at 3000 your rods are probability still in the down position if you are only cruising. So the big part of the rod needs to increase. The off idle cruise under 2000 might still be on the idle circuit and that's the reason it's good. One rod larger should get you to 13/1 two steps should be 13.5. The cruise is the big part of the two step rod and the smaller end is for power mode.
Last edited by second 70; 06/22/16 05:01 PM.
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Re: Tuning...a/f readings
[Re: Cab_Burge]
#2096376
06/22/16 07:09 PM
06/22/16 07:09 PM
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Joined: Oct 2003
Posts: 7,506
Az
Crizila
master
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master
Joined: Oct 2003
Posts: 7,506
Az
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I like to see 14.8 to 15.8 AFR on idle and part throttle cruise at engine operating temps, not on start up To lean out the main circuit at or above 2500 RPM try enlarging the bottom step on the primary rods, both sides Leave the part throttle step the same size, if you can 14.8 to 15.8 will boarder on a lean miss condition, especially if you have any fuel distribution issues at all ( reads most single plane manifolds). I don't use AFR readings much for setting idle mixtures. Prefer using best vacuum and idle rpm. Best way to address those one or two lean holes IMO.
Fastest 300
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