Weber Tuning. LM-1 and Dyno. Database, Information, Troubleshooting, Graphs.

[kucharskimb]

I hope that you will find this informational and educational. I also hope that those of you with similar information will post on this thread in an effort to compile a tuning database. Many threads have useful information, but most stem from troubleshooting a particular problem… If you have info to further troubleshoot this setup, please add it. I’m happy to take new readings with different configurations.

I would like to thank Mike Hughes, aka starlifter1, for loaning me his Innovative LM-1 monitor. I would also like to thank Richard Parr, Henry Bieker, Grady Clay and Steve Weiner. I consulted each of them during my troubleshooting and they each proved to be a wealth of information.

My engine specs are:

71 2.2E stroked to 2.4E. estimated compression 9.6:1
0 deg advance on cams
Crane XR3000 optical pickup ignition with dwell control
PS-91 Coil
Jacobs Wires
NGK BP6ES plugs gapped to .045”
SSI’s with a partially gutted stock 2 in / 1 out muffler

I built this engine in 2002 when I was in San Diego and had Mech Tech Motorsports set up the carbs on their dyno. Mech Tech sets up many sandrail Bug and Porsche engines and are familiar with Webers. In the end, the car made 172 RWHP. At this time, the Weber configuration was:

Italian Weber 40 IDA 3C
34mm venturies
70 Idle jets
130 Main jets
180 Air correctors
F26 Emulsion tubes
4.5 Secondaries
Continuous taper mixture screws

When I asked what the AFR was, he said that they aim for 13:1. I didn’t ask any more questions and lived in bliss for 3 years…



Well, sort of… I always seemed to have wet plugs. They weren’t really fouled with carbon and junk, but they just seemed to be damp. At the time, I was running B7ES (non-platinum). Consulting with Richard Parr, he suggested performing a compression check. If it was less than 180psi, he suggested running BP6ES plugs. He said 165psi was about the break line for going one step hotter to BP5ES. All of my cylinders came in at 165-170psi, so I switched to the BP6ES’s.

Last year, I attended one of the dyno runs here in Seattle after we moved from Cali. The technician would not let me finish my runs as we were running too lean. Granted, it was a cool day, but the AFR’s were too lean beyond a 20-30 deg temperature correction. This is the graph that I left the shop with that day…



I was obviously concerned about the transition from 3-3800 RPM, as well as the leaning at 5000RPM.

[kucharskimb]

The techs suggested going with larger main jets in an effort to bring the whole curve down. So, on the next dyno day, I left with these graphs…



One step higher 130-135 mains made a sizeable difference, lowering the AFR to manageable levels. The 140s didn’t seem to change anything compared to the 135s. Also, to note is that the RWHP is still in the neighborhood of the original dyno in San Diego: 172 --> 163 RWHP

But, hey, let’s not just let that be good enough… I noticed when I was hooked up to the dyno that before I went to WOT, the cruise and idle circuits were in the neighborhood of 11:1AFR. That might explain why I had always had wet plugs.

So, off to another local Weber tuner to buy some idle jets. He suggested going from 70’s to 60’s as a start.

With the following configuration, this is the information that I was able to gather using an LM-1.

Best Idle was at 13.5:1. Each 1/20th of a turn on all six mixture screws was equal to .5 AFR. Each ¼ turn of all six air corrector screws was equal to .5 AFR. Increasing the main jets .05mm richens the mixture at WOT .5-1:1.

When looking at the graphs, an initial lean, then rich condition reflects a lag in my accelerator pumps—still working on that problem… I don’t know how to discuss spikes throughout the graph other than “noise”. The spike at the end of each run is usually due to me lifting my foot from the throttle prior to stopping the recording.

My designation for each graph is: Idle/Venturi/Main
The numbers below each graph are steady cruise in either 4th or 5th gear down the highway.

60/34/135


This is a pull in 5th gear down the highway.
Idle and cruise info:
Idle AFR is 13.5-14.0:1
The following are AFRs at steady state cruise in 4th and 5th gears.
2000 12:1
2500 11.5:1
3000 11:1
3500 11.5:1
4000 13:1

[kucharskimb]

At this point, I solicited the help of the Big Four at the top of the page. Grady said the plugs were too hot. Richard said the plugs were too cold. Steve said the muffler was screwing things up. And Henry wanted me to verify many things before we proceeded. What they all agreed on was this: 34mm venturies were too big—go to 32s—and step down the idles to 55s.

So, I did. But first I reset the floats with the gauge. They were each a little low. Now the meniscus is set between the two lines on the gauge. I also verified that all cylinders were pulling the same amount of air and were synchronized. A second compression check verified that all cylinders were still 165-170psi. Fuel pressure is 3.5 psi in the engine compartment.

I re-ran the 34-60-135 configuration and got the same numbers as above.

I swapped the 60s out for 55s and got the following:
Cruise AFRs leaned out .5 across the regime to roughly 12:1 across the board from 2000-3500RPM. Performing a 4th gear pull up a long, steady hill:

55/34/135


I now wanted to see how the 32mm venturies were going to change things. Up to this point, the theory was that the 34mm venturies were too large to atomize the fuel at low speeds. After working out the numbers again for correct venture size:

1) Divide the volume of one cylinder in cc's by 1000.
2) Divide the RPM where peak power is made by 1000.
3) Multiply the number derived in 1) by the number derived in 2).
4) Take the square root of the number derived in 3).
5) Multiply the number derived in 4) by 20.

.390 * 6 = 2.34
Sqrt 2.34 = 1.53
1.53 * 20 = 30.6

Consequently, 30.6 would be the ideal venturi. Sheds a little light why the 2.0 had 30mm venturies. However, you also have to take into account the equations that dictate (.8 * the bore size) is the ideal venturi for that carb.

.8 * 40 = 32

So, 32mm venturies it is…

The following are runs with different idle and main jet configurations using the 32mm venturies…

55/32/130


Idle 13.5:1
2000 14.2:1
2500 14.2
3000 13.5
3500 13.3

[kucharskimb]

60/32/130 – a little scratchy, but try to follow the actual line


Idle 13.5:1
2000 12:1
2500 12:1
3000 12:1
3500 13:1
4000 13:1

55/32/135


Idle 13.5:1
2000 14.2:1
3000 13.5:1
3500 12.8:1
4000 12.5:1

So, where do I sit now?... I'm running the 55/32/130 configuration. I’d like to get the transition smoothed out and still need to put the new diaphrams in the accelerator pumps. Perhaps new emulsion tubes to bring the mains on earlier. I have been told to raise the float level to bring the mains on earlier is a possibility. The car actually seemed to accelerate most smoothly with the 60/32/130 configuration, despite it running rich during cruise.

When looking at AFR vs Hp and Efficiency, you can see that there is some leeway surrounding the 12.5-12.8:1 ratio for maximum power. From 11:1 to 13.5:1, Power is very acceptable. And if anything, you would rather be on the lean side of this, towards stoich at 14.7:1 than on the rich side, as you are just flushing fuel away…

[911pcars]

HI Matt,
Thanks for sharing that information and for the organized testing methods. There's plenty of data to extrapolate for other engine setups.

Sherwood

[Steve@Rennsport]

Hi Matt:

Nice work,...

I would suggest the F3 emulsion tubes and keeping the 55 idles for a good lean cruise. The F3's bring the main circuit on a bit quicker for E cams and up and helps when using larger main venturies.

[RoninLB]

Idle 13.5:1
2000 12:1
2500 12:1
3000 12:1
3500 13:1
4000 13:1



Idle 13.5:1
2000 14.2:1
3000 13.5:1
3500 12.8:1
4000 12.5:1



are these #'s etc under acceleration ?

[jluetjen]

Just another observation -- if your engine has the stock 2.2E heads with the stock 32 mm intake ports, I'm not sure how any carb venturis bigger then 32 mms will result in additional HP, at least that's my theory. The intake ports will choke-off max RPM air flow, while the large carb venturis will not give good low RPM performance -- which may be the root of your issues.

[kucharskimb]

steve
thanks again for all of your help. i'll start scrounging for some F3s

Ron
the numbers below each graph are steady cruise in either 4th or 5th gear--whatever was safe down the highway.

John
yeah, that's a good point. i let someone talk me into the 34's when i was gathering parts for the rebuild. i originally was going to open the heads to 36mm ports, so maybe that's why i purchased the 34's. it ends up being like the guy who puts two holley 750 double pumpers on a stock small block chevy... cool on paper, lousy performance...

[RoninLB]

[QUOTE]Originally posted by kucharskimb

Idle 13.5:1
2000 14.2:1
3000 13.5:1
3500 12.8:1
4000 12.5:1

?... I'm running the 55/32/130

------------ I think you should adjust your idles all equally just above lean. Steady 4th or 5th at 3k just rich of lean bucking.
12.7 - 13.1 is great for max power afaik and the in-between rpms and power is just really dialing it in to be drivable and ready for wot.










I’d like to get the transition smoothed

------------ It seems that your mains are becoming predominant by 3,500ish. The shape of the e-tubes seems to richen from 3.5k foreward. If so it's not heading towards lean at 5k-6k. But maybe you need them to come on rich and lean out the higher rpms as w/F3.
What do you mean about transition smoothed?
Is it when you accelerate or at a steady 3.2k ?






Perhaps new emulsion tubes to bring the mains on earlier.

------------- afaik the thing with e-tubes is first deciding if you want them to either start lean and then richen or start rich and then lean. F3 e-tubes must come on rich then then lean afterwards, afaik so far.

If the issue is acceleration then that has nothing to do with e-tubes afaik. Acceleration is its own circuit just as idles and mains.







I have been told to raise the float level to bring the mains on earlier is a possibility.

------------ then your affecting the idles and mains together. Your adding more fuel head. If mine I'd find the best setting and fuel psi and that's it.. period.
You don't have to adjust the carbs with fuel head. And besides if you add more fuel to a good mix you chance, in general, crashing power. That's easy to do when tuning the acceleration circuit.






seemed to accelerate most smoothly with the 60/32/130 configuration, despite it running rich during cruise.

---------- I run a tad rich on the idles as it makes for a nice package. It starts rich and leans out by 2.5-3.2k. My mains really don't take over till around 3.8k. It richens up around that point from the idles. It'll run a little rich from 4-6k with steady throttle or accelerating.. again my e-tubes are perfect for my act.

That has nothing to do with acceleration. Richer acceleraton fuel flow than necessary crashes power big time. You shouldn't have to run rich idle and mains to make up for a lean acceleration circuit fuel flow.

Acceleration should be dialed in after the idles and mains are ok.

Maybe run 4th or 5th at a steady 3k. Set all 6 idles equally. Find out how far you can lean before it starts bucking. Richen all 6 equally in 1/4 turn increments. Then set the idle floor a little rich above bucking. Do the same at 3.5+k also to find out you main circuit floor. If you have 125 mains to try? And do the same for all in-between.

If there is a hole anywhere then it gets adjusted per that circuit or the wide influence that the e-tubes have afaik.

Once that's doable then it'll be time to play with the acceleration imo.







some leeway surrounding the 12.5-12.8:1 ratio for maximum power.

---------- it's best to be a bit rich than a bit lean of peak power A/F ratio as it has less of a detremental effect per deviation afaik. I think your e-tube is a better issue? Do you need them to come on rich and then lean or visa versa? And which ones? Which is widlely recommended? Too rich and combustion cools causing a loss of power when it may be unwanted. Then again maybe it's wanted?

So far it sems that the leaner the better is your operation ?








And if anything, you would rather be on the lean side of this, towards stoich at 14.7:1 than on the rich side, as you are just flushing fuel away…

----------- You're also controlling the CHT. What happens if you're crusing 110F desert at 90 mph on the lean side? Your oil temps rise, etc etc.

In general afaik there is more of an issue of running carbs rich than running them lean? It's easy to find lean steady rpm operation and then run just a tad richer.


1/4 idle turn is slightly noticable. 1/2 turn is a noticable difference in power.


Meanwhile you've done a great job logging your info. On that I assume that your carb air adjustments are perfect and both carbs are in sync with each other using 2 meters? The cross linkage allows both carbs to be equal through various rpms. Getting 6 individual cylinders producing equal power ain't easy.

[kucharskimb]

ron,

13.5 AFR at idle was the leanest i could go to avoid snapping during decel.

the transition at partial throttle is fine with the current setup. the transition at WOT is not. the above graphs are all at WOT. i know i have to work on the accel pumps. they are clearly not giving me the response i need as i have to turn the throttle shaft about 1/8 turn to activate the squirters. i would also be curious to see how a shorter squirt would affect the acceleration.

as far as smoothing out the transition, i was refering to WOT and how the AFR goes lean just before transitioning to mains during acceleration (3-3500RPM), and then goes excessively rich at the beginning of the main jet circuit (4000RPM)

ron, which e-tubes and cams are you running?

i've tried to follow your advice on setting all of the mixture screws equally. i believe on your new PMOs, this is possible. however, mine runs like crap when i do this. i believe there are 6 screws for a reason on my 40 year old technology carbs.

same bank airflows are perfect and cross bank airflows are perfect at idle, 1500 and 3000 RPM when activating the throttle using the throttle hold inside the car.

1/4 turn on all six mixture screw is like changing the AFR by 1.5. it is way more sensitive than that. fine tuning is a turn the width of the screwdriver slot, minus any backlash from the spring.

the LM-1 uses voltage to read other data (there are 6 channels in all). i would like to tap into the tach sending wire and see what kind of signal it is. i don't know if i can write in an equation to the program, or if it has to be a linear relationship, ie 1V = 500RPM. if the tach signal is linear, we might be in luck... i'm still going off of the curve from the dyno, then placing the LM-1 graph underneath it and comparing curves. if it has shifted left or right, i currently do not know.

[RoninLB]

[QUOTE]Originally posted by kucharskimb [QUOTE]



the transition at partial throttle is fine.. the transition at WOT is not.
------------- that's good news as it should be only the acceleration fuel flow that's the prob.



i know i have to work on the accel pumps.
--------------- set up the linkage so it triggers correctly. Test all squirters to determine what's happening. All squirters should flow equally. Test drive and see what's happening. If it tends to bog they are too rich. Adjust till acceleration runs lean and then slightly richen the flow. Set acceleration squirters to flow no more than necessary. Excess flow does not increase acceleration.

they are clearly not giving me the response
------------ meaning it boggs? Excess flow crashes combustion power. I assume ignition is correct? CIS ignition curves can be set up for carbs.


as far as smoothing out the transition, i was refering to WOT and how the AFR goes lean just before transitioning to mains during acceleration (3-3500RPM), and then goes excessively rich at the beginning of the main jet circuit (4000RPM)
--------- desktop guessing I would say the linkage is late. The squirters will drop combustion temps normally. The idea is not to crash the temps as when squirters are flowing too much fuel.


ron, which e-tubes and cams are you running?
--------- I would follow Steve's recommendation above then once the engine is running ok you can "maybe" dial it in further.

I'm running E cams



i've tried to follow your advice on setting all of the mixture screws equally. i believe on your new PMOs, this is possible. however, mine runs like crap when i do this.
---------- It's even in the Weber book to adjust all equally. If all is ok with your engine maybe there is a prob somewhere else? It seems that generally idles can be set between 2-3 turns. If you set them unevenly then some will be running rich and some somewhat lean. Don't forget you have 6 indivudal carbs for 6 indivudal cylinders. The game is to get them to produce power equally. Maybe one or two idles need to be set 1/8 turn differently. That adjustment is another story.

Try setting them all equally again. Set them as lean as possible with the engine running decently.



i believe there are 6 screws for a reason on my 40 year old technology carbs.
--------- it's because you have 6 indivudal carbs instead of a common plenum.




same bank airflows are perfect and cross bank airflows are perfect at idle, 1500 and 3000 RPM when activating the throttle using the throttle hold inside the car.
----------- good. That means you are using 2 air flow meters? If this is not right you'll be chasing your tail in circles trying to dial in the carbs. 4-5,000 rpm idle testing should confirm everything.




1/4 turn on all six mixture screw is like changing the AFR by 1.5. it is way more sensitive. fine tuning is a turn the width of the screwdriver slot, minus any backlash from the spring
--------- 1/8 turn of the idles is barely recoginized in power. 1/4 turn is noticable. I wouldn't use the AFR to get the carbs fine tuned now. Max power in 5th is another story.




the LM-1 uses voltage to read other data
----------- you are reading a combination of cylinders instead of each cylinder. Personally it's not worth much more than entertainment at this stage.

[kucharskimb]

ron
always happy to provide entertainment for the rest of you...

you're the only one i know with an EGT setup on webers. so i need you to do a little homework for us and post your findings here.

1. with all of your mixture screws set exactly equal, please post one of your EGT graphs at idle and at, lets say, idle plus 300 RPM.

2. write down your one mixture screw setting, and set it aside so you can reset your carbs after the experiment.

3. screw each mixture screw in individually until the motor bogs--just one cylinder at a time. screw it out 1/4 turn at a time, until you get no further increase in engine RPM with your quarter turn. if you want, add another 1/8 turn out.

now move to the next 5 cylinders and repeat. all i'm looking for is to maximize engine speed with as little fuel as possible. i would suspect that you will have different mixture settings for each carb. don't bother counting turns, just maximize the RPMs and save the fuel.

4. once you have done all six and are happy that there is no snapping and popping, repeat the EGT reading at idle and idle plus 300RPM. please post that result here as well.

5. then report the individual mixture screw settings for comparison with your graph.

my theory is that, and you said it above:

"it's because you have 6 indivudal carbs instead of a common plenum."

therefore, i need six individual mixture settings. if you use your six screwdrivers in your six arms and turn all six mixtures screws down simultaneously from 2.5 turns, and stop doing so once the engine starts to bog, then back out to maximize RPM, you have really only affected one cylinder. ie, only one cylinder went lean during the process, and is now running near stoich. the other five are still running fat.

so there's your homework. appreciate the educational benefits of your setup.

[RoninLB]

Originally posted by kucharskimb

1. with all of your mixture screws set exactly equal, please post one of your EGT graphs at idle and at, lets say, idle plus 300 RPM.
------------- idle EGT is inaccurate info in general. Too many variables and EGT readings is not lab info. Actual combustion temps would provide that.



3. screw each mixture screw in individually until the motor bogs--just one cylinder at a time. screw it out 1/4 turn at a time, until you get no further increase in engine RPM with your quarter turn. if you want, add another 1/8 turn out.
------------ You can use that routine to get a general idea of what you turn all 6 idles to equally. 1/4 turn will have a noticable affect on EGT. Let's say you have most idles +- 2.5 turns. Turn all equally to 2.5. Shut engine and let cool. Pull plugs and clean them. Even if they look clean clean them anyway. Way down inside where the porcelin hits the steel is the tricky part to clean for me. I use a tooth brush and solvent. Then run the car for at least 10mi to clean out starting carbon and see how it feels at cruise at about 3,000 rpm in 4th and 5th. Pull over somewhere and turn all 6 idles down 1/4 turn. Run for another period of time and watch for lean popping at cruise. If no lean popping do routine again till popping. When it starts popping in cruise turn 1/8 turn rich till popping stops. This routine is a cruise measurment Not acceleration. You can also do this routine at 4,000 to test your mains at cruise.




now move to the next 5 cylinders and repeat. all i'm looking for is to maximize engine speed with as little fuel as possible. i would suspect that you will have different mixture settings for each carb. don't bother counting turns, just maximize the RPMs and save the fuel.
------------ you are not saving fuel if each combustion is at a different temp than the others. This so called deviation is inefficent for producing total power as one powerful piston is draging along a less powerful piston. I would guess that this also creates more engine shaking.




4. once you have done all six and are happy that there is no snapping and popping, repeat the EGT reading at idle and idle plus 300RPM. please post that result here as well.
-------- decent EGT reading at 3,000 rpm is done in 4th or 5th gear. Idles are set as per correct operation of that circuit. What happens at idle is what you're left with. Just like setting timing to 35deg max. What the timing is at idle became insignificant if you have a good dizzy curve.



5. then report the individual mixture screw settings for comparison with your graph.
------------- In the early days of setting up my carbs I tried all kinds of experminents just to see what a bad set-up looked like. The "deviations" and overall EGT temps were the tell tale of what's happening to efficency and thus performance. One interesting issue was a "seat of the pants" acceleration circumstance where idles and venturi were wrong but the "seat of the pants" felt great as operation went from lousy to decent during acceleration. The contrast is what is noticable. It wasn't running great it was only feeling great.




my theory is that, and you said it above:
"it's because you have 6 indivudal carbs instead of a common plenum."
--------- text will say that carbs are inefficent induction and that fuel injection into each combustion area is best. That deviation with carbs will be about 90-130+F and deviation with FI will be down to around 75F. Mine produce less deviation than high end FI. This can only be a meaningful number when the engine is operation where EGT readings are providing info, which is not at idle, 1st gear, 2nd gear, or 3rd gear. Simply put carbs is little more than pouring gas into the combustion chambers with a bucket. You adjust the 3 circuits of your carbs to perform best when they are supposed to perform best. What happens when they are not operating at best is insignificant to tuning.




therefore, i need six individual mixture settings. if you use your six screwdrivers in your six arms and turn all six mixtures screws down simultaneously from 2.5 turns, and stop doing so once the engine starts to bog, then back out to maximize RPM, you have really only affected one cylinder. ie, only one cylinder went lean during the process, and is now running near stoich. the other five are still running fat.
-------- I think Webers have indivudal vacuum ports behind a plug. You could hook up 6 vacuum gauges and set idles to max vacuum. It's not the best but it's better than the "ear" method.


If I start doing experminenting with idles set differently my plugs will foul and nothing will be accomplished except to prove what doesn't work. BTDT


I would suggest using NGK BP5ES adjusted to .028 till you're dialed in then setting them to .040 if you're using MSD. That .040 was a recommendation from a local pelican pope.

Plugs foul easily and will throw off your adjustments. Keep them super clean while this is going on.


Set idles and mains just rich of lean popping at cruise. Adjust accelerator flow just above lean. This will max your combustion power and temps without running lean. Excess fuel cool combustion and decreases power.

[kucharskimb]

i guess that means NO.

i'm happy to send you money for a new set of plugs and for employing your services.

[RoninLB]

Originally posted by kucharskimb


i'm happy to send you money for a new set of plugs and for employing your services.

not necessary


Drive the car over here and I'll pay for the plugs. I even have a couple of sets of BP9ES to play with.


what plugs are you running now? Sometimes plugs can be just dirty enough to make tuning a pia. Whatever they are keep them clean.

[kucharskimb]

So, today I called four separate Weber tuners:

Carbs Unlimited
Inglese Induction
Weber Parts Direct
Bieker Engineering

All four technicians said it was acceptable to have all 6 mixture screws in different settings. i asked if +/- 1/2 turn was acceptable and all said well within reason. Inglese actually pointed out that on old carbs, it could be a problem of worn screw seats. he also said that sometimes the tension spring will give a false seat. Bieker agreed and said there were so many variables in tolerance, that it was unlikely that they would ever all be the same.

They all agreed that on out-of-the-box carbs, the tolerances should be much tighter.

the Weber tuning books suggest as a last step that the plugs be pulled and examined to make final mixture screw adjustments. The instructions also use the word "synchronization".

[RoninLB]

Originally posted by RoninLB

i've tried to follow your advice on setting all of the mixture screws equally. i believe on your new PMOs, this is possible. however, mine runs like crap when i do this.
---------- It's even in the Weber book to adjust all equally. If all is ok with your engine maybe there is a prob somewhere else? It seems that generally idles can be set between 2-3 turns. If you set them unevenly then some will be running rich and some somewhat lean. Don't forget you have 6 individual carbs for 6 individual cylinders. The game is to get them to produce power equally.

Maybe one or two idles need to be set 1/8 turn differently. That adjustment is another story. [/B]

"another story" is using one or more Colortune units.

maybe still at 1-201-584-9370


God bless your fortitude.