A/F ratio- Tuning with the LM-1

[Zach Gomulka]

I don't know about that. I think this tool has taught me quite a bit in a short time. I still have a long way to go, but I'm getting there

[Allen Wiess]

If you ignore all of it and just spend the time jetting and test driving, you'll get it done alot faster and the engine will run way better than listening to some computer.

Or just get rid of the dinosaur pissers and go EFI      ......... What the hell are jets 

[Jim Ratto]

Man, if these Zeniths are this much of a bitch, Sheep, aren't you glad we AREN'T using one?!

[dirk zeyen]

  EFI is oldschool in 2040 so what the hell is EFI 

dirk zeyen

[Zach Gomulka]

Nawww, I don't think they are bad at all. My only gripe about the carb is that you have to take it off the manifold in order to access the fuel jets (right next to the fanshroud). The carb top has to come off the get to the airs as well, so jetting is a little more time consuming than average. The motor is running very sweet now though, I'm happy

I still have yet to try out the 130's because I'm a little doubtful that they will work. When I get a little extra time on my hands I'll give it a shot and let ya'll know.

[Zach Gomulka]

I got the 130's in, and just as I expected it was a little too lean under light acceleration- like mid 15's to mid 16's. It had a bit of a stumble right at that point, as well. But the full throttle A/F ratio is much better- it went from the high 10's to the high 11's. So I took out the 140 idle airs and swapped the 120's back in to try and richen up the midrange, and WHA-LAA! It's right back to where it was in the middle, and leaner under full throttle Next I'm going to try a smaller accelerator pump jet... I'll let ya'll know what happens.

I don't care what anyone says, the LM-1 kicks arse

[dirk zeyen]

problems with zenith: ask doctor zach!!!

dirk zeyen

[Diederick/DVK]

sounds like it's quite a task zach!
how do you connect an LM-1 anyhow?
good luck on it

[Zach Gomulka]

sounds like it's quite a task zach!
how do you connect an LM-1 anyhow?
good luck on it

Very simple to hook up... I made a spacer at the collector flange with an O2 bung welded in, and I installed a few "hidden" power outlets under the rear seat. I'll post some pics later.

After a little more driving it still seems a tad bit lean on the mid range- tolerable for this altitude (over 5,000ft), but maybe not so much for lower elevation. I'm going to keep the LM-1 hooked up for the trip to Vegas (2500ft I believe) this weekend to see what happens...

[67worshipper]

was it much money then zach? may invest in one myself. id like to tune the idas for myself really

[Jim Ratto]

was it much money then zach? may invest in one myself. id like to tune the idas for myself really

I bought the NGK AF sensor. A friend of mine that dyno tunes Porsches turned me onto it. NGK AFX sensor.

[Zach Gomulka]

A while ago I pulled out the 28mm venturi's, and swapped them for a pair of 25's that were in my parts carb. I could never get the 28's to work perfectly... there was always a compromise somewhere. So I did that, put the idle fuels back down to 40's with 140 airs, and installed 125 mains. I didn't loose much on the top end power-wise, and it is much more driveable now. I also got 28mpg a few weeks ago on a trip down to Phoenix (mixed Interstate, freeway, and city driving). So I was pretty happy with that... but I tried another change- 185 airs instead of the 230's. Didn't change a thing, so I'm leaving it as is. Here is how I had it set up in my car- spacer adapter at the collector, wires through the quarter window, powered under the rear seat, monitor sits in the console so I could glance at it easily.

[Zach Gomulka]

So in hindsight, I should have just swapped the 24 vents for the 25's and left everything else alone! It was an educational experience though

[marcd]

was it much money then zach? may invest in one myself. id like to tune the idas for myself really

Innovate Motorsports lists their "Basic" kit starting at $349.95

http://www.innovatemotorsports.com/products/lm1.php

The Basic Kit ($349) includes the LM-1 meter, a Bosch wide-band oxygen sensor, 10 ft sensor cable, cigarette-lighter power adapter, serial cable for PC connection, 9V battery, exhaust bung and plug, CD and quick-start guide.

There is a neat DIY wide-band out there which is quite a bit cheaper and works just as well as the LM-1.
http://www.14point7.com/JAW/JAW.htm

JAW is the lowest priced wideband oxygen sensor reader ever.
Product Features:

$45 DIY Kit: Without Display
$70 DIY Kit: With Display
$80 Assembled: Without Display
$115 Assembled: With Display
Uses the inexpensive Bosch LSU Wideband Sensor.
Accuracy to 0.01 Lambda.
2 programmable outputs
Free Air Calibration
Real-time datalogging
User selectable refresh rate of 8-255 [hz] for digital display
Reads from 0.69 [Lambda] to 2.33 [Lambda]
Reads from 10.18 [AFR] - 34.28 [AFR]

This will likely find it's way on my car after I am finished with the new exhaust. 42's are nice but I am getting horrible mileage.

[John Maher]

I don't consider the LM-1 a serious tuning tool
Lack of accuracy and its inability to cope with moderately high EGTs make it worthless for ACCURATE mapping/jetting

Maybe this has been addressed with the introduction of the LM-2 

[LGK]

I don't consider the LM-1 a serious tuning tool
Lack of accuracy and its inability to cope with moderately high EGTs make it worthless for ACCURATE mapping/jetting

Maybe this has been addressed with the introduction of the LM-2 

I have to agree with John on this one.
I like the wideband-commander from dynojet a lot or the motec system.

Steve

[Zach Gomulka]

I need a little carb basics 101!

What about the needle and seat?
So please educate me; if it is too small then the bowl could run dry, but if it is too large then the float would just stop flow, correct?? Does the size effect driveability?? If so, in what way? I can get different sizes from this guy, and if I can pick up a little free mileage or power in some way I wouldn't be objective to that. Or should I just shut up and keep what I've got in there??

[Fiatdude]

I set mine @

idle 11.6-12.2
cruise on idle/progression 12.8-13.2
cruise on main (freeway) 12.0-12.7
full open throttle 11.5-11.8

perfect -- unless your turbo then 11.5 everywhere

[K-Roc]

I set mine @

idle 11.6-12.2
cruise on idle/progression 12.8-13.2
cruise on main (freeway) 12.0-12.7
full open throttle 11.5-11.8

perfect -- unless your turbo then 11.5 everywhere

 Hi,I finally have my new map all tweaked in ( Megasquirt )  2332 With 044 heads 9.8:1 comp

You set up your Air fuel ratio target  12X12 grid with map/RPM then load in some basic VE numbers and go for a drive, the Megasquirt slowly zero's in on your desired A/F numbers, the hard part is finding the right road to get to 7200 ROM in 4th gear 

Idle is around 13.8 ( can't get it any leaner with an FK47)
Light cruise and low load Highway 14.7-15:1  ( no cooling problems what so ever)
Full load Max torque is at 12.8:1


11.5-11.8 under full throttle with a N/A engine is pig rich.  try around 12.8 as see how much crisper it runs.  The best test here is a Dyno or Trap speeds in the 1/4

[Bruce]

What about the needle and seat?
So please educate me; if it is too small then the bowl could run dry, but if it is too large then the float would just stop flow, correct??

Too small for the inlet valve and you run the risk of emptying the bowl.  Engine goes lean.
Too large and the fuel level will exceed the set point when the valve opens, causing the engine to momentarily go rich.  Then lean.  Then rich.......

There are simple guidelines in the Weber carb manuals.  Engine hp determines the inlet valve size needed.  How much hp do you have?  What size is the stock inlet valve in your carbs?

[Zach Gomulka]

Thanks, Bruce. You saw my motor... I'm lucky if I'm pushing 60hp!
Single Zenith applications came with a 1.75, duals were 1.25's.
I guess since I'm not experiencing any rich/lean problems, I should just stick with the 1.75

[Bruce]

1.75 is on the big side.  1.5 would be better.  But if you're having no trouble, don't mess with it.

[Zach Gomulka]

I'll try the 1.50's... I've got nothing to lose

[Fiatdude]

was it much money then zach? may invest in one myself. id like to tune the idas for myself really

I've got a LM-2 -- Used it to tune the Fiat for about a week and it has been setting of the shelf since so it is basically brand new -- make me an offer

[Zach Gomulka]

Screwed a 1.50 in there and all seems well. The Zenith used to have a bit of an issue with sweating fuel, this seems to have solved it