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914World.com _ 914World Garage _ How close is close enough...
Posted by: computers4kids Nov 17 2013, 09:31 PM
I've been playing around with metering rods, springs, and jets for my Edelbrock 600 on my conversion SBC teener, using primarily a vacuum gauge and AEM wideband. I'm currently getting these type of readings
Idle-around 14.5
Cruise Mode--light throttle: 13.7
Power Mode--Heavy Acceleration: 12.3
I'm curious what kind of ratios you carb guys run? The car runs great, but I just wondering if I need to lean the power mode out. The motor likes these numbers and the plugs look good.
Also curious, anyone with FI have some numbers available from their wideband?
Thanks, Mark
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Posted by: ConeDodger Nov 17 2013, 09:48 PM
You'll get better mileage with a leaner cruise but if the motor seems happy, that is the right tune... 
Posted by: Mike Bellis Nov 17 2013, 09:57 PM
My idle is 18-23
Cruise 14-17
under boost 8-10
But I'm EFI and turbo. But the engine really likes it! 
Posted by: JRust Nov 17 2013, 10:12 PM
My idle is 18-23
Cruise 14-17
I like that ratio. I need to learn my Stinger software. I stay in the 12-14 range but seems a little squarely sometimes. Goes lean on acceleration instead of rich? Not all the time but all I have done is mess with the trims in it. Just need to spend time learning that system & how to adjust the AFR specifically.
Posted by: Mike Bellis Nov 17 2013, 10:21 PM
My idle is 18-23
Cruise 14-17
I like that ratio. I need to learn my Stinger software. I stay in the 12-14 range but seems a little squarely sometimes. Goes lean on acceleration instead of rich? Not all the time but all I have done is mess with the trims in it. Just need to spend time learning that system & how to adjust the AFR specifically.
That partially why I went with a factory ECU and not a programmable. Way more computing power.
Posted by: brant Nov 17 2013, 10:52 PM
Water cooled motors like slightly different numbers than air cooled. You would be well served by checking your numbers on the Chevy forums.
Your number for heavy load should really be taken at redline and not just at load
Posted by: Andyrew Nov 17 2013, 11:09 PM
You can lean it out a little bit for your primary jets and richen your secondary jets to get cruise closer to 14.5.
I think my idle is dialed in around 17.
Anywhere in the 12's is fine for a carb'd SBC at WOT.
Posted by: Andyrew Nov 17 2013, 11:12 PM
My idle is 18-23
Cruise 14-17
under boost 8-10
But I'm EFI and turbo. But the engine really likes it!
Mike, your really between 8-10 at WOT? Wow that is rich. I would have thought they would have tuned it closer to 10-11. Turbo cars Do like to run rich especially modern tuning with lots of timing.
But they are literally the experts on that engine... so
Posted by: Mark Henry Nov 17 2013, 11:26 PM
For an air cooled engine you really want to be looking at a cylinder head temp gauge right beside that A/F meter.
If that's a type 4 those readings are good, they need to run richer than a WC engine.
Posted by: AfricanHijinx Nov 18 2013, 11:29 AM
I like your dash pad
Posted by: sgetsiv Nov 21 2013, 09:17 PM
I'm just getting started on carb tuning - been running way too rich for the last few years. Currently running 55 idle jets and 150 mains - EMPI HPMX Dual 44mm on my Raby 2315.
I installed an AEM wideband AFR a few months ago and am getting the following readings:
At idle - 11.0 to 11.5
Cruising in the 3500-4500 rpm range - 11.5 to 12.5
WOT 2500-3000 rpm range - 10.5 to 11.0
WOT 4000-6000 rpm range - 12.0 to 12.5
Planning to try 52 and 50 idles and 145 and 140 mains over the next few weeks.
Posted by: 72hardtop May 18 2014, 12:28 PM
I'm just getting started on carb tuning - been running way too rich for the last few years. Currently running 55 idle jets and 150 mains - EMPI HPMX Dual 44mm on my Raby 2315.
I installed an AEM wideband AFR a few months ago and am getting the following readings:
At idle - 11.0 to 11.5
Cruising in the 3500-4500 rpm range - 11.5 to 12.5
WOT 2500-3000 rpm range - 10.5 to 11.0
WOT 4000-6000 rpm range - 12.0 to 12.5
Planning to try 52 and 50 idles and 145 and 140 mains over the next few weeks.
Your AFR at idle has everything to do with your mixture screws and nothing to do with your idle jets. Your mixture screws are out to far. LBI should be around 13.0.
What distributor are you using?
Only tune lean (part throttle cruise) if your using a vacuum advance distributor. If your running a centrifugal only distributor shoot for 13.2 (+-.5) across the board.
Your too rich WOT. During acceleration 12's are ok but at WOT steady you should be at 13.2 (+-.5)
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