[Firebob]

I'm determined to get a tool to tune my AFR. I'm looking at the LM-1. I've heard it said that 14.7 is the magic to reach for. Should I be tuning for the same numbers at part throttle and WOT also? I thought I read that more like 12.5:1 would be better at WOT.
This'll bug me until I get it done.

Robert

[Hammered]

Holley says:
13:1 - 15:1 @ idle
12.5:1 - 13.5:1 @ moderate load
12.5:1 - 12.7:1 @ WOT/peak T
13:1 - 13.2:1 @ WOT/peak HP

[Scott Stoneburg]

for my car, it has ran best at mid 12s to 13s at WOT.

[wheelspin]

Robert,

Check out the FAST wideband afr meter, about $400 from Summit, including TWO O2 sensors. I have used mine to lean out my Pontiacs @ cruise, gaining 10-30% mpg improvements in the process. The cruise circuit is my primary focus as the motor spends only a small % of the time operating in the other circuits.

Les

[GOAT8U2]

Summit is selling their package of the LC-1 for $250, it literally says it comes with the Innovative software.

I like the Holley AF/R charts but
At idle it could be around 15:1 and up a tad with no worries since there isn't a load.
14:1 while cruising is plenty safe since a lot of EFI cars are 15:1 and up on the highway.

I'm low 12's on E85 but would be mid to high 12's on straight gas for max power.

[Firebob]

Thanks for the numbers.
I saw the Summit package but I'm not looking for a permanent display, just want to tune it and take it off. And if I decide to, I can get the rpm attachment so it would be easier to monitor revs at the same time.

Robert

[BILTIT]

I have this installed, have not used it much yet though.

http://www.zeitronix.com/Products/zt2/zt2.htm

[Cliff R]

"The cruise circuit is my primary focus as the motor spends only a small % of the time operating in the other circuits."

Good post Les. We have found through a lot of testing that different engines and drivetrain combinations require different A/F curves, there is no set standard, pretty much just "ranges" that most will fall into. In any and all cases, tune the engine for what it wants, rather than chasing a particular number around with a A/F monitor. It will drive you nuts anyhow, and changes slightly from hour to hour, day to day, season to season.

As far as track performance is concerned, the Stock and Super Stock cars use engines with much great VE than most of ours, and they only have to run a few seconds at a time. They can run right up on the jagged edge of the "curve" for best possible performance. For street and street/strip engines, I'd er slightly on the "fatter" part of the curve, rather than attempting to run leaner ratios and end up with a few pistons in the oil pan!

FWIW, I've ran the A/F on our engine clear across the range with secondary metering rods from .028" to near .060", in .005" incriments, on more than one test and tune session. The entire spread of ET is usually barely a tenth and less than 2mph. Unless you are splitting hairs, no need to spend a lot of time tuning in that area. These days I don't even bother with metering changes, I just leave the sames rods in the carburetor year round. Broke that rule the other night after blasting off 3 runs within .02 seconds of each other. I went 4 thousands smaller with the metering rods, and lost .05 seconds and .5 MPH, pretty surprised actually, as the air temps were cool, humidity wasn't that great, but still better air than the last time we were out......Cliff

[70judgeconv]

I did buy the summit lc-1 kit and I am now tunning with it. It does come with all the innovate software and connections. You can even down load your run from the track to your computer. I installed this tuesday night so much learning is still to come. Jeff Emil { shaker455] says to look for 12.5-13.5 for best performance.

[shaker455]

Originally Posted by 70judgeconv

I did buy the summit lc-1 kit and I am now tunning with it. It does come with all the innovate software and connections. You can even down load your run from the track to your computer. I installed this tuesday night so much learning is still to come. Jeff Emil { shaker455] says to look for 12.5-13.5 for best performance.

Actually 12.5 to 13.0

[amcmike]

Idle: Best vacuum reading (can be as high as 16:1)
Cruise: Best vacuum reading (as lean as possible without bucking) can also be as high as 16:1
Moderate loads: 13:1 - 13.5:1 @ moderate load (not including tip-in "pump shot)
WOT: 12.5:1 - 13.0:1

OEMs target 14.7:1 because it is required for most catalysts, and still provides decent economy (and uses the least expensive 02 sensor design).

Remember that as you lean out the idle and cruise, make sure you properly compensate your transition circuits. Many people tend to disregard tuning the transitional-type circuits and compensate with the idle, main, and if applicable, secondary main circuits. Thus they conclude "the engine likes a richer setting." For instance, most carbs have at least 7 tune-able areas, and you need to work with all of them to achieve the maximum balance of economy, power, and driveability. As one example, on a Holley 3310 you can adjust the idle screws, main jets, secondary jets, power valve, accelerator pump diaphram, accelerator pump cam, squirters, secondary springs, and choke setting, without even getting into major surgery (like bleeds and boosters).

Best order to tune:
1) Idle
2) Main Circuit, Primary (for cruise)
3) Main Circuit Secondary (for constant WOT exclude transition period from cruise to WOT)
4) Part throttle enrichment
5) Pump shot (transition to WOT enrichment)
5a) Secondary opening (if applicable)
6) Choke

[Tom Vaught]

Quote:

"OEMs target 14.7:1 because it is required for most catalysts, and still provides decent economy (and uses the least expensive 02 sensor design)."

Required by law that you run at Stoich (14.7) everywhere these days.

Tom V.

[Skip Fix]

Remember too idle circuit affects transition and cruise/main circuits to a moderate extent too, not just idle.

[amcmike]

Originally Posted by Skip Fix

Remember too idle circuit affects transition and cruise/main circuits to a moderate extent too, not just idle.

And further, primary main circuit will to a moderate extent will effect secondary results (in the case of a 4bbl carb). Which is why order of tune listed in my previous post is so important.

P.S. If you are tuning a Holley, for gosh sakes don't use the primary jets to tune your WOT. Either buy the correct size secondary jet plate, or convert to screw-in secondary jets if it doesn't already have them.

[chuckies76ta]

So having said all that, How do you lean out a Holley part throttle circuit.. ? In other words, Cruise and part throttle.

Thanks
Charles

[Skip Fix]

"And further, primary main circuit will to a moderate extent will effect secondary results (in the case of a 4bbl carb). Which is why order of tune listed in my previous post is so important." Agree even on a Q jet everyone says to "just use the secondary rods as tuning" WOT- a jet change on the primaries makes a big difference there also.

But you can have the idle fine and it is too fat as the main circuit comes on until you get higher in the primary range.Sometimes leaning the idle circuit leans your part throttle on a Holley. Sometimes you have to start tweaking the main bleeds, the emulsion holes- and can screw up a good carb!

I personally can live with an idle off. My car idles fine anywhere from 11-15.Now at 15 off idle has a flat spot the accel. pump can't solve

[chuckies76ta]

Thanks Skip Fix.. Anybody else..

Thanks
Charles

[Firebob]

Bought an LM-1 unit yesterday. All this Holley talk is fine but I'm more in the qjet area of carbs. I'm going to try and make it as simple as I can. I figure three regions to work. Idle, part throttle/cruise and WOT. If I can get these areas dialed in I'll be happy again.
I thought the deal was that gas/air burns at optimum at a mix of 14.7:1. I didn't know it was a government mandated conspiracy.

Robert