Clicking the Fuel Adjuster Left

[Pawel66]

After fixing the fuel delivery issues last year my idle somehow got out of tune.

Did the linkage tour by the book. Checked again WRD closing and CSV not leaking.

I am clicking the adjuster left, I lost count, the split linkage test still indicates the car runs rich on idle. Exhaust fumes smell, exhaust pipe gets black on idle, engine hesitates a bit when pedal pressed to start...

Will I screw the adjuster screw out of thr FIP when I click to the left too many times?

By the symptoms I should lean the mixture more.

[ja17]

Pawel, also do the split linkage test at higher RPMS. If it is still rich at higher RPMS then you may need a rack adjustment or a baro compensator adjustment.

[Pawel66]

Joe, thank you, I will do this. I got access to CO tester, I will know exactly.

I checked the baro compensator before - it works and there are no more shims to be removed.

When I was struggling with mixture before I did the rack adjustment - many clicks to the right to lean the mixture. Exhaust pipe is grey after ride.

How far left can I go with idle adjuster or how far right can I go with rack adjustment? Will there be a stop or I will just screw them out of where they are causing trouble?

[ja17]

The idle adjuster can be turned a lot of clicks. Eventually the clicks become less pronounced.  This is your warning. The clicks might eventually feel very faint or disappear altogether. This is definitely too far. As the screw clicks it moves rearward and moves away from the leaf springs that create "the click". The screw may move so far back that it can fall out of its threads or trap the adjuster knob and cause it to stay engaged.

[Pawel66]

Clear, thank you!
i think I am not there yet. In my FIP the adjusting screws are behind the plate, so it is relatively easy to get there (did that before to replace the oring on adjuster screw).

What I feared was that I will mess something internal up.

Thank you for your kind attention!

[PeterPortugal]

Guys,
This might be a dumb question.....but how do you do a split linkage test at higher rpm?
Regards
Peter

[stickandrudderman]

Simple. (if you have two hands).
You rev the engine to 2000rpm and disconnect the rod to the pump. Push the rod down (to add fuel,  let it up to reduce fuel) with one hand whilst maintaining the position of the rest of the linkage with the other hand.
If the engine runs better as a result of either of these two actions you have identified a fuel delivery problem.

[PeterPortugal]

Thanks Colin.....luckily I have two hands !

[Pawel66]

I think if you had three hands it would be even better...

That moment of revving up to 2k and disconnecting linkage - I would have a hard time holding the linkage steady and disconnect the rod with one hand.. unless you disconnect first the rod and just press the ball joint against the ball (to have it centered) while revving up...

Anyway - the idea and way to do it are clear - thank you! The rest is just a matter of a number of hands.

[PeterPortugal]

Pawel - if you didn't know either then it wasn't a dumb question...so here's another.

Does it matter if you choose to keep the fuel steady and give it less or more air?

[Pawel66]

I was also trying to imagine how to do the split linkage test at 2 or 3k rpm and I am happy you asked and I appreciate stickandrudderman paid attention and advised.

I really appreciate experienced Members' patience and devotion to explain to people like me the same simple things again and again.

I was always told there are no dumb questions and I agree with it. However, when I read some of my questions I asked, I begin to hesitate...

I am not sure if there is a clear recommendation on what to keep steady and what to add. I think you need to manipulate both to determine hypothesis and to verify it.

I think the purpose of the exercise is to broadly (!) determine if there is more or less balanced amount of fuel and air in the mixture or too much of one of the components (which would mean there is too little of the other). So when you add fuel a bit (air steady) and the engine stalls, this suggests the mixture is rich. Then to verify this, if you add a bit of air (fuel steady) and engine revs up - this confirms the mixture is rich.

And vice-versa for lean mixture.

When I had a good (more or less) mixture - the changes in the way engine was running were not significant and they were more about how even it ran rather than revving up or stalling.

[ja17]

I think you have the general idea Pawel. Note that with the split linkage test at idle warm, the RPMS should be able to increase by opening the venturi slightly (200-300 rpms). In this way the air screw on the intake manifold can be used for minor idle rpm adjustments at any time.

[Pawel66]

Joe, yes, clear, thank you!

On the other hand, if the engine revs do not react to the idle air screw - the venturi is set wrong, it is not closed.

Thanks again! I will be fighting this uneven struggle during the weekend. I hope the CO tester will come handy. My biggest wprry was the clicking left with idle adjuster or right with the rack adjuster - with mixture still too rich... which would indicate other issue in the system (CSV, baro, WRD), which I checked before and they seemed to be ok, with a note that there was no more shims to remove.

Also: someone here mentioned to me that when you remove the breather tube from the valve cover, you will get a different (lower) reading of the CO. I saw no reference, however, to it on the forum and I assumed that, even though it makes sense (as there must be carbohydrates coming to intake from the breather), in the properly working engine it should be negligible or taken into account in the norm.

[ja17]

If the warm engine does not react to loosening the large, slotted air adjustment screw on the intake, then a slightly too lean condition exists. This may be caused by a venturi not closed, incorrect IP mixture setting or incorrectly set engine linkages etc.

[Pawel66]

Ok, thank you, clear!

[Pawel66]

I think I might have identified the issue for rich mixture (low and high rpm) - it looks like my WRD seems not to shut completely when warm. It used to be ok couple of years ago, but it may not be ok now.

I feel a slight suction when engine is warm (thumb, with filter removed). It is slight and it goes away once in a while, but it is there. It is slight regardless of rpm.

Please confirm kindly, if I may ask, that even slight suction should not be there, before I dig into posts figuring out how to fix it to get leaner mixture.

[Pawel66]

I did some studying on the WRD and wanted to wrap up conclusions and the next steps (not re-inventing the wheel, just trying to be a bit systematic and hoping for your input and kind advise):

1. I am working on overall rich condition of the engine, during idling and on higher rpm as well.
2. Before getting to rack adjustment, checks on several parts (CSV, barometric compensator, WRD) revealed small air leak through WRD when the car is warm (this was garage warm up, I will verify this after driving warm up).
3. This air leak may be caused by
a. only air valve leaking/not closing while the WRD pushes lever in FIP to decrease fuel supply after warm up - this may not cause the rich condition
b. both fuel and air increase supplies are not completely cut off (as the whole assembly of thermostat pin, air valve, spring and plunger does not move down enough) - this would cause the rich condition
c. separately - as I do not remember exactly the oval shim situation I checked in the past - I need to verify again how many and how thick shims I have there - this may cause the rich condition too

So what I think I need to do:
1. Disconnect and plug the coolant hoses, disconnect the air hose.
2. Remove the upper and lower WRD assembly together and take it to the bench (seems to me the best way to avoid coolant pouring to the lower WRD part)
3. Note the oval shims configutration
3. Disassemble the WRD, check the movement of parts, note the round washers configuration
4. Check the thermostat in a pot with water (how many mm extension - need to look up)
5. Check the plunger rod travel (I did not note how many mm it should extend in hot water, 7mm? not sure, I will try to look  it up), I saw 1.1mm for older type pump

I have the R25 pump.

Any watch outs from you, any advise?

[Pawel66]

Please kindly advise what should I do.

I have the WRD out.

I do have the oval shims: 2x 0.5mm and 1x0.2mm

I have 1 round shim 1mm.

The pin at the bottom was moving freely with travel ca 9mm.
Pushed in: 22mm from housing base
Extended: 30mm, which gives travel of ca 8mm

The air valve is relatively tight in its cylinder, but moves with some resistance and it holds air very tight.

Thermostat
Ambient: ca17mm from its collar
80 degC: ca22mm from its collar, giving travel 5mm

When assembled back together for test:

Ambient:
Pin sticking out 22mm from WRD base, 8mm from bottom

ca 85C
Pin sticking out 27mm from WRD base, 13mm from bottom, 5 mm travel
Air is cut off completely.

So travel due to temperature change is 5mm.

Air not cut off when pin sticks out 11-12mm (75-80C).

What do I do?

It seems to me I could use one more round shim 0.5 to 1mm to have air cut-off at lower temperature.

My rich conditoin is ca 8% CO at idle and over 15% at 2500rpm.

However: I was looking for the proper travel of the pin driven by thermostat and I found what BenzDr was saying: "The 230SL thermostat has a very short travel at about 1.5 mm while the 280SL has about 7 or 8 mm of travel. If the late system won't shut off at a fully warmed engine, you can add  round shims at the top of the slide valve until there is no longer any vacuum with the air filter removed".

Shall I then assume my thermostat is bad (too short travel) and replace it first? That would mean I do not need round shim and I may not need to remove oval shims.

[wwheeler]

Hi Pawel,

If I read your post correctly, your engine is rich at idle and at higher RPM hot or cold? Not sure if the function of the WRD shims has been explained. The oval shims change the mixture ONLY when the engine is cold. The round shims changes the time when the WRD shuts off. The round shims do NOT change the mixture of a cold running engine.

If you want to change the mixture over the entire range hot or cold, I have found shimming the B. compensator to be the easiest. Be careful as it is super sensitive. A .003" shim makes a world of difference. The WRD affects the mixture for a cold engine and only at idle. It serves the same function as a choke on a carburetor. 

Does the WRD air shut off at around 70*C (160*F)? I believe that is near the correct temperature. I read that yours has a slight suction. If slight means you can barely feel suction, then that can be normal. The air valve does wear over time and will not seal 100%. What temp engine coolant thermostat are you using? If it is a cold rating, the engine may not be getting hot enough to completely shut off the WRD. That happened to me.     

Hopefully that helps.

[mrfatboy]

To add to Wallace's explaination, since you have an overall rich condition you must remove shims from under the BC to lean out your pump. Like he said it is very sensitive.

[Pawel66]

Gentlemen, thank you for your kind replies!

I have no shims to remove from under the barometric compensator. The BC pin extent dimension seems to be within specs. It is not that that makes the mixture rich. It is not the leaking CSV either.

Yes, I know WRD and its elements are for cold running (and I have rich mixture when warm, I do not look into cold running mixture at this stage). But what if the pin at the bottom of the WRD is not long enough to cut off additional fuel with thermostat fully extended?

I understand that in the WRD when the thermostat is shrunk, the lever in FIP pushes up the pin at the bottom of WRD and this lever is in its up position. This is causing additional fuel is supplied and additional air is delivered. As the thermostat expands, it pushes down the plunger/spring/air valve assembly. What happens now is - the air valve closes the air holes, cutting additional air delivery and the pin (bottom end of plunger) pushes down on the lever in the FIP - cutting off additional fuel supply.

Is this how it works?

Then what if the pin at the bottom of the WRD does not push down enough to cut the fuel supply?

[Benz Dr.]

I would add round shims in the slide valve or replace the thermostat for the WRD. All air should shut off and any vacuum leaking is a sign that you may not have full shut off on the slide valve. You must be sure that you have obtained full movement to final stop on the slide valve or you will always have a rich running condition.

My guess is that you may have to do a lot of reverse tuning if you replace the thermostat. I can't emphasize enough how important it is that you have 100% shut off on the slide valve.

[mrfatboy]

pawel,

You are correct about the operation of the WRD. 

How about this theory?

There is also a rack adjustment screw that is accessed located by the solenoids.  It does the same thing as the BC adjustment. I'm wondering if someone has adjusted it so far out if range causing your rich condition that the BC adjustment can't even compensate.

[stickandrudderman]

My guess is that you may have to do a lot of reverse tuning if you replace the thermostat. I can't emphasize enough how important it is that you have 100% shut off on the slide valve.

Dan, I have to respectfully disagree.
A small bleed at the auxiliary air slide is just the same as undoing the idle screw half a turn and can be easily compensated for in tune-up.
Obviously a large and unchanging bleed is a different matter but as long as there a big noise at that orifice when cold and a little or no noise when hot I'm satisfied.

[Pawel66]

Dan,

Thank you - I have to proudly say my thinking was along the lines you stated. Yes, I may be chasing the correct settings once the thermostat is replaced. I am not sure if then I need to add a round shim as valve will be pushed further down than today. When I was pouring water from the kettle to the thermostat tower and blowing in the pipes I htink I was missing a 1mm or so to be sure the air is shut off. If I follow your statement from years ago, that the thermostat pin travel should be 7-8mm, I am short there and a new thermostat should solve the issue or move me forward at least towards the shims.

Stick,

I am not competent enough to get in the discussion between two Gurus, but my simple thinking is: I am not worried so much about the leak as such, but rather a leak that is a symptom of WRD not shutting down and continuing delivery of both fuel and air. A leak because of the valve not tight - fine, but a leak as the valve is not pushed down enough - that may be a different story.

mrfatboy,

Yes, this is very likely. This someone could be me a couple of years ago or the Bosch service. I think it is more likely to be a Bosch service as a couple of years ago I was after leaning the mixture like today. Othr place who touched the FIP was where it was re-built - Bosch service. But.. the rack adjustment is counter-intuitive (especially after adjusting idle screw) clicking right is leaning.

Priceless posts from all of you, thank you!

[wwheeler]

I can say with 100% certainty that a very small air bleed is a possibility and not a worry as Stick says. When I noticed the small air bleed on mine, I added round shims until the WRD shut off so early it wasn't then doing its job. And yet, the small air bleed was still there. The air valve piston has no seal other than trace oil that is between it and the housing cylinder. So it makes sense to me that given wear over time, a 100% seal is just not realistic.

Something that gets overlooked on the WRD operation is that the rod that contacts to IP lever, is spring loaded. And in fact, there is a stop down in the pump that will prevent that rod from continuing to lean the pump as the thermostat bulb keeps extending with temperature. JeffC discovered this and is in the tech manual I believe. So if you go beyond the normal engine operating temperature, the WRD will not continue to lean the pump. The spring loaded rod will just compress further. If the stop is adjusted correctly, the air valve should shut off at roughly the same time the rod hits the stop screw in the pump. This just popped into my head when you mentioned that the rod may not be going down far enough.   

Adjusting the BC is just an easier way to adjust the full range on the pump. It does not mean that anything is wrong with it. I prefer that over the screws in the back of the IP which is like a can of worms unless you are very knowledgeable. If you don't have any BC shims, then you may have to mess with the rack screw. On my BC, there is a thick washer and maybe a 1mm thick. You could replace that if you have it, with thinner shims.

Replacing the thermostat may also be a good idea and I do not believe it is very expensive. Good luck.

 

[450sl]

Pawel, I have had my wrd not closing 100% as well and added a small 8mm dia Or so shim of 0.4 mm : now my wrd closes completely. For the overall rich situation I would first think of the oval shims

Mark

[Pawel66]

You added the round one on top of air valve or oval one, below the base? I suppose the round one...
Yes, this would be a solution for me, as I thought, thank you.
But if the thermostat is not working as it should - I think I would just replace it. Then I will take it from there.

[Pawel66]

Wallace, I read those posts from Jeff. That contributes to understanding of how the WRD works, it was very informative.

On the adjustments - yes, the BC seems to be the easiest, but I have no shims there. It may happen, however, that, if someof the theories are right, that I would need to add shims to BC.

I have absolutely no intention to go into the adjustments of the black and white screws under the lid. It is the full range adjustment and idle screw that I would touch if I need to. I think it is manageable even with a primitive Gunsons. We will see.

Thank you for your thoughts!

[mrfatboy]

Pawel

Reread Wallace's #18 post. The oval shims only control mixture during warm up.

Since you are rich over all rpm ranges. I would suggest the following.

1. Put WRD back together
2. Verify that Air slide valve is completely shut (minimal air suction) AFTER the car is completely hot.  Just warming up in garage takes too long or might not get it completely closed.
3. Adjust rack in back of pump leaner. 

[Pawel66]

mrfatboy, yes, thank you. WRD works on warm up (that is when it affects mixture) then shuts off.

The doubt is if the WRD indeed shuts off. If it does not - WRD will cause rich condition across the rpm range. I suspect the thermostat may not extend as long as it should be. I will risk $130 and replace it. If it does not help - yes, I will be back to rod adjustment. I just want to eliminate all the factors that are suspicious. CSV was ok, BC was ok. WRD does not seem to be ok - so I will fix it. I do not know other/further factors, other than adjustments.

[Benz Dr.]

Dan, I have to respectfully disagree.
A small bleed at the auxiliary air slide is just the same as undoing the idle screw half a turn and can be easily compensated for in tune-up.
Obviously a large and unchanging bleed is a different matter but as long as there a big noise at that orifice when cold and a little or no noise when hot I'm satisfied.

Yes, but that's not what I said or at least not what I meant. Full shut off is a reference to fuel shut off. Air, as you indicated, can be compensated for if not too much.

I think Pawel gets how it works which is why we discuss stuff like this - so we can all learn from one another. 

[Pawel66]

I received my new thermostat (picture enclosed).
Then I did the testing, picture with results enclosed (sorry for format). It looks like I found my 2 mm. The temperatures might have varied a bit - it is difficult to hold steady temperature in a kettle... but - old one stps at 5mm travel, the new one goes 7mm travel, then stops.

The air shuts off at ca 80 degree.

I will put it all back together in the car and see what I get in CO results/rich condition.

Do I put sealant between thermostat and its housing only, or also somewhere else? e.g. where the oval shims are?

Is there anything that should be inside the air filter? Any foam? Felt? Mine is empty...

[Pawel66]

I put everything back together and into the car. And I need your kind asdvise.

The new thermostat extends 2mm further than the old one - I think I eliminated thermostat as potential source of additional fuel supply due to not complete additional fuel shut-off after warm up. At least I have to assume this.

Before: fairly steady warm up (rich), revs down at 85deg or close, air shut-off (not really complete) at close to 85, then smooth but rich idle (8-9% CO) and rich higher revs (15-17% CO - but not sure, it took Gunsons long to stabilize).

Now:
1. A bit rich warm up ambient to 60 deg (could be normal);
2. 60-80 deg very lean warm up, tendency to stall, stalling sometimes, need to hold throttle a bit to keep it running or hold FIP lever a bit
3. Near 80-85 getting rich again
4. Air still shuts off at 85 or close; feels a bit late... (garage warm up)
5. Then smooth but rich idle, leaner than before (6-7% CO); higher rpm rich as well, a bit leaner than before

In essence:
1. I leaned warm up (not surprising); will have to come back to it, but probably later as the main topic is rich idle and rich high rpm; will
2. Given that the last potential cause of richness was supposedly taken care of (fuel shut off)
a) add a 0.5mm round shim to have the air cut-off a bit earlier?
b) go back to rack adjustment and idle adjustment screws?
C) once this is done, add a, say, 0.5mm oval shim to enrich the warm up?

Please kindly advise.

[mrfatboy]

Hi Pawel,

I have access to a Gunson CO tester also.  Just yesterday we ran a cold start CO test on another member's 250 SL for fun.  He has the European configured pump.  His car was sitting for a while and we just wanted to see what it would do and compare with mine.

Tests 1-5 were done on my 280sl last January.  I ran the tests with experimenting with oval shim thickness and fip idle screw.

Yesterday's test is marked 250 SL. (Orange.  He will be tweaking based on what we found.  I think he will just use idle air screw to lean out as his idle RPM's only hit 900

To run the test I used the Gunson and an iphone.  I downloaded the Fast Camera app that takes a picture every two seconds. Started the car and let the camera do it's thing.  I then copied the results into an excel file.  I could send it to you if you like so you can graph your own data.

You can see by the first high curve is were the CSV injects the fuel, rack is pushed forward and the trough is when the WRD pin hits its stop in the FIP and just the remaining air from the WRD air slide valve is closing up.

You could do the same test and see how yours compares.

But to answer your adjustment question....

If it were me I would adjust the rack to make leaner over all rpms.  I say that because you said you played with it a couple of years ago and might have turned the wrong way.  Also  your BC has no shims left for adjust.  You just slowly have to walk your way back.  Hopefully you can get it to a point to add some shims back into the BC.

[Pawel66]

Thank you! This looks like a very good and hel[ful material!

I di not set the Gunsons for the warm up. My conclusions are based on split linkage tests. I will check it as you did.

Truth is that when I plugged in the probe the engine was after some time of standstill, a little cooled down. and initially for some minutes the reading was 5% - that might have been equivalent of the dip in your graphs after fuel was shut off and some air still coming in. Then the reading on idle went higher, to the level of 7-8% during regular idle and stayed there.

I think I will start the rack leaning then.

Does the rack adjustment affect warm up mixture? Or the warm up is fully controlled by the WRD?

Thanks for sharing!

[mrfatboy]

Adjusting Rack screw clockwise leans pump over all temps and rpms (same as BC adjustment)
Adjusting Rack screw counter clockwise enriches pump over all temps and rpms (same as BC adjustment)

[Pawel66]

Yes, thank you - I remember that, it is opposite to idle screw.

"All temps and rpms" - so it does affect mixture during warm up, I understand.

[Pawel66]

I am a bit lost and need some kind advise again...

I keep turning the rack adjuster clockwise to lean the mixture across the ranges.

What responds so far is the idle - I leaned it dramatically, so for the end of the day I had to enrich idle with idle adjuster, left it at 4% CO for now.

But then when i press the pedal, observing the time intervals Gunsons require, practically no matter after how many clickds I have 8% CO at 1500rpm and 10-11 at 2500rpm.

I lost count of clicks. Not because I cannot add, but because I lost a feeling of what a rack adjuster click is. Sometimes it feels like half of turn, sometimes like quarter of a turn, sometimes is pronounced, somtimes less pronounced - I am lost there.

It is logical - I was leaning idle in the past, so overall leaning "cought up" with leaned idle. But what worries me is that at medium rpm I see no reaction. I think I turned the adjuster ca 1.5-2 turns. I do not seem to be hitting the threshold that is visible on CO meter...

Should I continue? Or the culprit is somewhere else?

I looked at my notes and confirmed today: I have both the throttle lever and FIP lever starting from the stops and returning to the stops at the same time. But when the FIP reaches max position, the throttle lever still has about 10mm travel to its stop. I disregarded it in the past (also not knowing how to fix it because linkage was set as per instructions, I have a hole in the shaft pedestal) thinking that this difference may not be critical (BBB says at least 1 mm extra travel for throttle). But maybe it is important?

[Benz Dr.]

IP lever should move to full stop and go back to idle at full stop. The throttle valve can be adjusted and should just grab a little bit indicating that it's fully closed. When fully opened it should be maybe 3 -5 mm from the full stop screw. If your full stop screw is adjustable someone may have moved it back. Do this adjustment on a cold engine!

The correlation between the IP and and the throttle valve is not a one to one ratio. Placed on a graph, the IP would appear as a straight line on a 45 degree plane. The throttle valve would look more like a bell curve with the beginning and ending touching the IP line. Both the throttle valve and the IP have to open at exactly the same time or you will have a stumble ( too rich ) or a flat spot ( too lean ) right off idle speed. This is not an easy thing to do by watching both levers and is in fact just about impossible to do that way. I place my finger on the IP lever and then I move the throttle linkage. When I feel the IP lever moving and see the throttle lever moving I know they perfectly synchronized.   

[Pawel66]

Dan, thank you.

I think I made pretty sure and correct syncronisation between the IP stop (which is given) and the throttle stop in closed position, then the legths of the rods, etc. Did it by the book. So when closed they rest at stops and raise from stops in the same moments.

Then when fully open, where you say throttle still has 3-5mm to full open stop, I have close to 10mm there. I do not know how to decrease it, actually..

I am not sure if this is can be the cause of the rich condition of 10% CO at 2500rpm...

[Pawel66]

I thought I had it, but I do not...

I managed to bring the CO level to between 3 and 4.5 (not sure how accurate measurements are with Gunsons) for higher rpm, up to 2500rpm. Idle at 4% CO. I was happy at the moment.

Then I took the car for a ride.

She seriously hesitates on acceleration from standstill or from low speed. Then I noticed she hesitates also when idling and revving up - but slightly, under load she hesitates seriously. I replaced the plugs, did not help.

She does not like this low CO level.

What do I do next? How rich is acceptable?

Make the idle richer? Will help to ca1200rpm...

[hkollan]

I was not happy with the Gunson CO meter at all. Not sure how much it can be trusted.
I never got confident with and was very happy when replaced it  with perfectly working Ex-Bundeswehr Bosch unit that I got off eBay. That still works as it should after more than 15 years in use here.
At least I would run the gunson against a verified pro unit to make sure the readings
are good.

Hans K

[Pawel66]

I agree, I do not treat it as a precise tool, and I will verify the readings. But it should be reading at least an approximate level, i.e. will differentiate betwen 10% and 5%.

What worries me is that when I got closer to where I should be, the engine hesitates when I press the pedal...

Tail pipes went from deep black to dark grey, spark plugs from soothey black to medium brown. This looks like leaner than it used to be, but not super lean yet... but I get a hesitation..

Not sure what to do next.

[mrfatboy]

It sounds like you need to start enrichening your Overall CO a bit by adding shims back into your BC. 

Then you will have to compensate your idle CO by going leaner a turn.

It's a balancing act. It will take multiple iterations.

[Pawel66]

That I think is one of the very likely ways...

What woud you say is a relatively safe level of CO at higher rpms (safe from the engine oil diluting standpoint, put aside legal and fuel consumption aspects)?

[Pawel66]

I followed the advise of one of the Members, put 2mm shims under the BC, leaned it back again with the rack adjuster and tuned the idle. Still warm up mixture to be fixed as per Mfb scientific approach.
I arrived at
5% CO at idle
5% CO at1500 rpm (this one is way above the norm)
3.5% at 2500 rpm

The car runs great and it starts when warm.

I hope these levels will not ruin the engine with frequent oil changes. I need to verify one more topic before attempting leaning it a bit further.

[Tom in seattle]

Are the WRD shims available?  I have no legal shims, just those I cut out of various materials and I don't know what thicknesses may be required. 

Thanks
Tom

[Pawel66]

Not to my knowledge. I saw many posts where Members were cutting their own. I also do not know what I need to adjust - doing some tests now.

I equipped myself with tools to cut the shims myself. Some say it is fairly easy if you use e.g. soda tins sheet metal.

[Cees Klumper]

I was just tinkering with this myself this morning. I have about 10 FI pumps sitting here in France and from 3 (the one in my car and two of the spares) I collected the shims, and I visually checked 9 more pumps. All have it seems between 2 and 4 shims. The ones I have in hand are of the following thickness: .5 mm, .3 mm and .1 mm. So it seems the stock ones vary in thickness in increments of .1 mm. Then there was one more that someone clearly made by hand, as it has a somewhat irregular shape, and it measures 1.3 mm. The pump on my car seems to warm up ok on 1.3 mm total shims. When I reduced it to .8 mm, it clearly was not happy and would not keep running from cold without constantly presssing the throttle just a bit (but not too mic or the engine would stall). I added back the .5 thickness and it was fine again. So the WRD is quite sensitive to the shim thickness. Which I guess was already clear from the fact that they are made in .1 mm for finetuning. It reminds me of the sensitivity of AC compressor clutches to differences of tenths of millimeters in their free play.

[Pawel66]

I am working now on the warm up idle mixture. If I have any findings on this topic that are worth anything, I will certainly share.