Pagoda SL Group
W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: col320ce on April 23, 2020, 04:36:34
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I'm trying to adjust the air/fuel mixture as per the last little bit of: https://www.sl113.org/wiki/Restricted/Linkage-tour and I'm having trouble with it.
Firstly the engine smokes like a chimney when you accelerate (it has done this since the cylinder head rebuild which was the first thing done when I bought it a few years ago). The engine was rebuilt some time in the past (bottom end as well) but there was electrolytic loss of the aluminum due to a stray current so I had to do more.
I've adjusted the linkages, valve clearances (and they were pretty good since last time) and confirmed TDC is all lined up (I used a dial indicator gauge to confirm).
I've connected the vacuum to the inlet manifold (see photo) and when I adjust the air screw to get best vacuum I also get a very fast idle (1200-1400). I've basically backed the screw on the injection pump all the way and I can't get the idle to go down (turning it anticlockwise when viewed from the driver's perspective).
I'm obviously doing something wrong but I'm not sure what it is ...
Any thoughts??
(64 230SL)
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Hi,
what do you mean with "I've basically backed the screw on the injection pump all the way" ? There are a lot of notches to back anti-clockwise (>60) to reduce CO and it's only relevant for idling. At speed, the amount of fuel to be delivered is taken from the setting of the control rod and is - more or less - not changeable. Maybe your whole FIP has to be overhauled.
...WRe
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I can feel that I can no longer push the screw in to engage it... So that's how I know where I am. An overhaul is mega bucks I'm told and I'm guessing it's too complicated to do myself? More than happy to do it myself if it's possible... I'll do a search.
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Hi,
some years ago we had a workshop with a specialist and the message was:"Hands off your FIP! You can't do anything without a test bench".
But these guys offer to check your FIP first for small money (~150€) to do a first analysis what's necessary.
...WRe
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That's not a bad plan... What's are their details?
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I am not a mechanic, but I went through a similar process.
If your car produces smoke like a chimney on acceleration (I had the same thing after re-build), it may do so for some time and then stop - if it is burning out some of the assembly grease that might have found its way here or there. But if it continues and if your spark plugs are black - your car may be overall too rich. If this is the case, you will not adjust it with the thumb screw that is sticking out in the back of the FIP, because this thumb screw is for the idle only, works up to ca 1700rpm. The overall FIP has to be adjusted first, then the idle part of it.
There is another screw for the overall range of rpms adjustment. There are also screws for partial loads adjustments, but do not even think of touching them.
You have all that info in Technical Manual. There is also massive amount of threads about it on the Forum.
If something happened to the idle adjustment screw, as you say, it is a bit of a trouble to get to it in your type of the pump (as you have this big nut probably in the back, rather then the simple plate) and because indeed it would be good to adjust your FIP properly (before any re-build decision) - it is probably best to send it to try to check and adjust it. Hope the shop will be honest and will not try to squeeze $$ from you.
One other important point: do not even think of detaching FIP linkage lever from its shaft as you work on your FIP.
While putting back FIP into the car, you would have to pay attention to its timing.
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are you speaking about the thumb screw on the back of the pump? if its backed out too far you will not feel the clicks. i have a spare pump that i can look at and provide inside pics
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Hi,
you should contact these guys and ask for a first analysis:
- https://classic-manufactur-goslar.de/
- https://www.oldtimer-technik.eu/
Both are recommended by German Pagoda forum Pagodentreff.de.
...WRe
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If you have your idle mixture screw turned all the way out ( or in ) and your engine is still running too rich the whole pump is probably running that way across all RPM ranges. In some cases it may be too rich at partial or full range but I start with the notion that I either have to add or subtract fuel. I turn the barometric compensator in or out until the engine idles smoothly and picks up throttle sharply. Before I begin I always mark the top of the compensator so I have a basic position for reference. Add shims ( out ) to make your mixture richer and remove shims ( in ) to run leaner. Generally speaking a big mixture problem usually needs anywhere from half to a full turn to cure. Your engine may not idle well after making this adjustment so you can tune with the mixture knob at the back of the pump.
Note:
compensator has to be completely removed to add or subtract shims and this is why you must mark your starting point before you begin. Aside from removing the compensator ( which can be really tight sometimes ) it's not that hard to do.
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Good info from Benz Dr. !
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This looks really easy! And, after some reading, a failed BC would have the opposite affect of reducing the fuel (although I may as well bench test it when its out).
This topic was very useful: https://www.sl113.org/forums/index.php?topic=12175.0
Thanks again ... Update at the end of tomorrow!
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good luck. benz dr always offers great advice
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If I am not mistaken, JeffC had the idea sometime back of jamming a rubber hose between the BC and the WRD tower to temporarily hold the BC in place while testing the car on the road. That way you can make quick adjustments back and forth until you get close. Then use the shims to finalize the setting. Mark the position of the compensator as the Dr. suggests.
Within reason, I always use the BC to adjust the total mixture and never mess with the screws in the back cover. It is just too easy not to use it. It is Very sensitive and even .003” can make a noticeable difference.
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If I am not mistaken, JeffC had the idea sometime back of jamming a rubber hose between the BC and the WRD tower to temporarily hold the BC in place while testing the car on the road. That way you can make quick adjustments back and forth until you get close. Then use the shims to finalize the setting. Mark the position of the compensator as the Dr. suggests.
Within reason, I always use the BC to adjust the total mixture and never mess with the screws in the back cover. It is just too easy not to use it. It is Very sensitive and even .003” can make a noticeable difference.
I agree. Using the BC to adjust fuel mixture may not be 100% fool proof but it's a whole lot easier to keep track of what you're doing. Marking the BC before starting is the key to everything because you need that as a point of reference.
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I removed the BC and the are two 2mm washers on it (total 4mm thickness) that have yellow paint on them. It looks to me that they were put on at the time that the pump was overhauled (there are yellow dots on the bolts holding it together too).
Before washer removal - about 1500 rmp, and to get best vacuum the air adjustment is screwed out a lot.
After removing one washer, the BC tightens up about 1.25 turns and the rmp goes down to about 1000 and the air screw is screwed in almost all the way (in fact it still idles well with it all the way in). In this state the split linkage test suggests this is a good air/fuel mixture. I'm assuming the average car has the air screw about half way which makes me feel whatever I am doing is incorrect and that I am now running super lean although I still can't get the idle rpm to lower.
And now ...
The engine idle drops after a while and the car stalls. This makes me think that there is a 'cold start' mechanism that may not be turning off properly and that I am trying to tune the car in a 'choke' type situation.
I'm unable to take the car for a drive as it's chocked into my carport and it's a 2 person, 30 min job to get it out (and I have no friends during covid ;) ).
Any thoughts??
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Are you starting the engine cold each time, and it stalls as the engine warms up? And your idle is high, but only as it is warming up but, once it is up to operating temp, does it then idle better/lower (beyond the 'window' during the warm-up cycle that it tends to stall)? There is a different set of possible issues during warm-up, compared to when the car is at operating temperature so it is important to know when your symptoms occur.
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I think the car is warm... I leave it a long time before starting the tuning. I make sure the top radiator hose is hot then let it idle another 5 or 10 minutes then start the procedure.
Once it is warm and I turn it off to make an adjustment I'm only waiting 20 seconds or so to make the next adjustment (it's only off for a minute or two.)
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check out this thread. take a pic of the bc stem and maybe we can tell if it has failed.
https://www.sl113.org/forums/index.php?topic=29130.msg210619#msg210619
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What puzzles me is that the car starts to stall after some time idling when already fully warmed up. That should not be and whatever causes that condition may also help explain your idling mixture problem.
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I had that and it was far too rich mixture.
When I had far too lean mixture, the idle was waving and stalled.
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I've done lots of reading and this is where I am up to:
Pulled the 7mm bolt from the CSV to make sure that there was no fuel leaking.
Put the BC back the way I found it with the 2 large washers and took some photos of it (from hex edge to tip is 21mm which should mean that it is good)
Checked the air line to the WRD is not damaged
Listened to the air intake on the WRD during start up ... there is good airflow but it does not turn off even when the car is "warm" (remember all I can do is rev the engine atm to warm it up.)
During cold start:
starts ok, revs at 800
the revs slowly increase to 1200 when the top radiator hose gets hot but are not really going beyond that no matter how much I rev the engine or wait
the split linkage test during start up gets a little bit more rev when adding air but this is minimal
WRD air filter sucks air and does not stop sucking air
there is an exhaust popping sound that gets worse as the car warms (not sure if this is pinging or not)
My Conclusion:
The car is either not warm so I can't tune warm idle
or
The WRD is malfunctioning ot at least should be turning off a little earlier.
I assume the next step is to pull the WRD and bench test it?
I have an early 64 230SL - I think this may have a bolt I can use to "turn off" the WRD ... can anyone ID the bolt from the photos (I've put a red arrow against my best guess)?
Thanks again to everyone
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I think I would hook a fuel pressure gauge up and see what it reads when the engine starts popping. Sounds like it is fuel starved.
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Just a voice from an amateur in case the fuel pressure test checks ok.
Does you temperature gauge say the car is warming up ok?
If it is sucking air when already warm, I think this may indicate WRD not working. So it is either not working in full (allows more of both fuel and air) or partially - shuts off fuel, but not air.
It is fairly easy to get a thermometer and a pot of water on the cooker and check if the thermostat is or is not opening as it should. You can do it with removed thermostat. You can also submerge assembled tower in hot water so that the thermostat housing is filled with hot water and try to blow air to see if the valve shuts off air in case the thermostat is working. Just lungs generated pressure is relatively small, bear that in mind.
I trust you went through WRD working and understand the oval and round shims topic.
Here is my struggle, car won so far: https://www.sl113.org/forums/index.php?topic=29221.msg212778#msg212778
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I've just pulled the WRD and bench tested it and it seems to be working. It shuts off the air when put into hot water. I managed to lose a round shim that flew through the air ... I'll try to find it tomorrow or assume it's 0.1mm and try to make another (I didn't measure it before it flew away).
So I'm either:
not getting the car to temperature
the WRD was stuck now it's fixed (it didn't feel stuck)
there is an issue with the water flow to the WRD.
I noticed a few comments that there was not much water in the pipes around the WRD when the pipes are removed. I found the same thing to... I'm not sure if there is a possibility of an air trap here so I'll get the thermometer onto the WRD thermostat housing tomorrow after I put it all together.
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In addition to Joe's suggestion on checking the fuel pressure, I would focus on making sure the air going through the WRD does shut off, otherwise I think you are getting false air throught it. The point in the warm-up cycle where it should shut off is not that long after cold start-up, certainly before the thermostat opens, I would think.
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It is easy to check if air is shut off - just remove the filter and plug the hole - see if the car still stalls or not. Also: when you remove the air filter, you feel very well with your thumb if there is suction.
WRD getting hot - the thermostat housing becomes bloody hot very soon as the engine warms up.
But again - on stalling when warmed up - I had it when idle was far too rich or far too lean, right around 80 degrees. I managed to check which way to adjust it by split linkage test and took it from there.
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When idling (not driving) I can't get the air to shut off on the wrd so I think this is my problem. It does get hot but a fair bit of air still flows. It seemed to work on the bench test so u assume I need to drive the car to get it fully warm (and off). So unless you think there is something faulty with the wrd I think I'll leave everything until I can drive the car to warm it up.
BTW the air filter has a lot of resistance in it (big difference in air flow with it on and off)... So I'll get one of these too
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Sometimes the metal coolant pipes to the WRD get plugged making the WRD stay cool and engine run rich.
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Thanks Joe... I'll pull them now and give them a clean.
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Well there was definitely a partial blockage on the top water pipe. It gets much warmer now but still not enough to turn the air off (but gets closer). I don't really understand this but I have ordered a new thermostat and FIP air filter.
I have just realised I have a PES 6 KL 70 B 120 R18 pump on my car which I think is from a 250 or later. If the pump has been swapped it's possible that it was never set up properly.
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here are some pics of the device. let us know if you have any questions. the air valve maybe stuck. water feed and return must be clear
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You have the wrong pump on your engine and it may never work right. You can try turning the BC to adjust to a leaner mixture but you're already paddling up stream.
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After the car stalls during warm up what do the plugs look like?
Toward the end of the warm up cycle the WRD plunger hits its stop first inside the pump. The air slide is the last thing to fully close. This causes a lean condition right before the air slide is fully closed. If your WRD is not fully heating up to close that last little bit of air off you will be in a perpetual lean condition. You mentioned before that you start hearing pops in the muffler which JA17 suggested fuel starvation (lean). Sometimes its hard or takes a long time to get that last little be of air slide fully closed just by idling.
Did you find your round shim that you lost? The round shims control at what temperature the slide valve starts to move.
When I have taken off my WRD there is plenty of coolant that pours out unless I plug the lines. You mention you don't have that much. Do you have the correct amount of coolant in your system? Possible air pockets?
One last thought, it's remote but you never know. Make sure the WRD is properly assembled. Pay attention to the round shims. If put in the wrong location the air slide can close then keep going a little bit and reopen on the other side. You never know who was in your pump before you ;)
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Dan ... If this was your car would you be getting the correct pump? Is that your advice for me?
I found the shim last night but it was not installed when bench testing and testing in the car (used a magnet to find it :).
In hot water it bench tested ok, so I assume I'm just not getting there without actually driving the car...
However, I found someone on a Jag forum with a similar (same?) thermostat and said that the new ones moved further and faster than his old one. Even though mine closed the air valve the plunger did not protrude as far as suggested in the technical manual.
So I have ordered new thermostat to rule that out. The hardest part I think will be getting it out of the housing ... any suggestions?
If that fails I'll wait until I have a spotter that can help me get it out of the carport so I can drive it to get warm...
If that all fails I'll look for the correct pump and get it reconditioned before putting it in.
One last thing, I haven't investigated the fuel pressure component; do I just attach this on the fuel line from the pump to the FIP?
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I'm not sure if this will help at this point but you can take off the air filter and place a mirror and watch the air slide close as the car warms up. At least you can confirm how much it actually closed.
Or course, as everyone has said before there should be no suction when the car is hot.
Another thought. Could the air slide be actually closed but just worn and letting air through? Using the mirror could confirm.
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So I have ordered new thermostat to rule that out. The hardest part I think will be getting it out of the housing ... any suggestions?
What do you mean here? Thermostat out of it s housing - that should not be difficult. If you have stone build up in the housing that prevents thermostat form being taken out of the housing - this whole thing will not work. You must have space for coolant there. If it is plugged with stone, the coolant is not heating up the thermostat, nothing works then.
Or I misunderstood something?
The thermostat whould expand about 7mm, I measured it some time ago. My old thermostat was expanding only 5mm.
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Thanks for the thought on this Pawel ... I pulled it a few minutes ago and there was lots of rust build up in there. It was very hard to get out; clamped the housing in the vice and got vicegrips onto it. Bench tested just the thermostat and got about 6.5mm travel so it's actually probably ok.
I'll put it back and test it on Friday and I'll try mrfatboy's mirror suggestion if it doesn't cut off the air flow.
I feel I'm getting close!
Thanks again everyone
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I truly think (which does not mean a lot due to my limited experience) that if you had coolant flow blocked by rust/stone build up inside the thermostat housing - it had no chance to work as it should have.
I think the later type of housing you can buy if it is difficult to clean it up.
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I think early thermostat travel is supposed to be 1.1 mm or about .050'' so it's not that much.
R11 pump is only used on a 230SL. Each of the three engines used in our cars use a different pump due to fuel volume requirements and other factors. The more displacement the engine has the more fuel is required to make it perform. So yes, I would be thinking about a R11 pump.
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At Mrfatboy's recommendation, I purchased an Innovate Motorsports A/F meter and have been pleased with its performance. I've been able to get my idle mixture and rpm correct and check the A/F ratio under acceleration.
https://www.innovatemotorsports.com/products/lm2.php
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Latest update... All back together after cleaning out the rust and it still is not stopping the air. I'm going to pull it all out again and measure the travel required to push the plunger far enough to stop the air. I assume I can add round washers to make this happen if I need a bit more movement. I also assume that to keep it balanced I would need to remove the same thickness of oval spacers that I added as round ones? I only have 2 very thin round spacers... Is there a "standard" total thickness range of these (I'm trying to work out if some have been removed).
Thanks!
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Perhaps some help there: https://www.sl113.org/forums/index.php?topic=29221.msg212778#msg212778
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Oval shims adjust mixture during warm up only.
Less oval shims = leaner
More oval shims = richer
Round shims adjusts the time when the WRD closes the air valve
Less round shims = later
More round shims = sooner
I seem to remember that there are usually 2 round shims. I forget the thickness but I know it's been mentioned before here on the forum.
I never bought a new thermostat bulb before. Does it come with a new spacer as seen in the below picture? I seem to remember there were two different thicknesses and they have to match.
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.../...a new thermostat bulb before. Does it come with a new spacer as seen in the below picture? I seem to remember there were two different thicknesses and they have to match
What needs to be correct is the opening in the washer (spacer) under the little thermostat so that the flange fits snugly. See attachment.
No sealing agent needed around this washer (spacer).
Use some, sparingly, on the conical flange between thermostat and thermostat "coolant housing" however.
Just a caution here: Never pull on the pin in the little thermostat; this is a sure way to disaster! :o
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Thanks Hans. I knew there was something different about them😁
Here is another good read on shim thickness and general subject.
https://www.sl113.org/forums/index.php?topic=15863.0
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I spent a lot of time adjusting the WRD with the round shims. The only thing they do is change the timing of when the WRD shuts off. The mixture is automatically changed by the device’s design. As it closes, it reduces the amount of fuel but also reduces the amount of air. You cannot change the mixture ratio via round shims.
I seem to recall I had two shims and was was about a 1mm thick. But that will be different between pumps. You just want enough shims to make the air shut off at the specified temperature. I think that is 150*F or 160 *F. Unfortunately, you just have to experiment.
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I've done some bench testing and these are the results:
The thermostat shaft extension from housing in specified water temperature (with no load)
19.5mm 55oC
19.5mm 60oC
21mm 70oC
22mm 75oC (no further extension in hotter water)
It needs a small amount beyond this to fully shut off and in the car I don't think it's quite getting to full extension but I'm not sure how to prove this (I assume this is because of the load/resistance from where the pin below engages with the IP). Is there a primary reference for what temperature the air will shut off at? I've seen everywhere from 150-180 (about 65-80oC). So I needs say 0.5mm more regardless, but if it should shut off at 60oC then I need to add about 3mm!
Both my shims look like 0.1mm so not helping much. I have 1mm washers that I can use and I can probably thin them if required too. I also have another thermostat on order but being in Oz and Corona and that the rest of the order isn't ready to be shipped yet it might be some time before it arrives. I'm kinda thinking I should just wait and see if it behaves differently.
Thanks again!
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I just looked at my notes when I did all of this work. On my pump, it took a minimum of .7 mm worth of shims for the air valve to shut. But that was near 180*F (82*C). You do not want the shut off to be that close to the operating temperature. So, I have a total of 1.3 mm worth of round shims and it shuts off at around 160*F (70*C). The more you add, the lower the shut off temperature is. Simple as that. Another by product of adding round shims is that your cold idle speed will be a bit lower. That is because you are reducing BOTH air and fuel by altering the length of activation in the pump.
I do not think the actual shut off temperature is that critical, and just do what works best for your engine during warm up. I think if you set the shut off between 155*F and 165* (68*C - 75*), you should be fine.
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Something that I should have done earlier is get out my inferred thermometer. I'm getting the housing only to about 58oC so I assume that I need to drive the car to get it warmer than this. There is still some air flow at this temperature although it is almost off. I have 1.2mm of round shims in there.
So the real question is: Is 58oC to cool to have it shut off? If not I'll just add some more round shims. Otherwise stop what I'm doing until I can drive the car.
Jeff mentions 50-55oC in post #21 of this thread: https://www.sl113.org/forums/index.php?topic=9244.0 I think this is in reference to the air shut off temp?
I am also a little confused about at what point the fip mixture is no longer being affected but the WRD. I assume it is when the pin is fully extended but I'm not sure if the lever in the injection pump reaches its full setting before this. I assume that I cannot sort idle out until the wrf/fip pin is a full extension ... therefore I need to get it up to 70oC as this is when my pin is fully extended?
Thanks!!!
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During warm up the WRD feeler pin extends into the FIP leaning out the pump. At the same time the air slide valve closes.
The feeler pin hits its stop BEFORE the air slide completely closes.
During this time, the FIP is in a lean condition until the airslide completely closes and thus completes the full warm up cycle.
That's why you need that airslide to close for the next adjustment step (full operating temperature )
Having that airslide valve close just idling can take time. Sometimes it does take driving it to get to proper temp. I guess you might consider yourself lucky that your car runs cool😁
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That's exactly what I needed to know MrFatBoy. I was thinking that a cool running car is also a good thing too!
I still have not measured the fuel flow. Is it recommended to use a flow meter for this or simply disconnect the fuel line and collect the fuel over a specified time? Is this done at the return hose near the fuel pump?
Thanks
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I have attached a chart of CO% over time during warm up.
This data has been collected from multiple 250's and 280's local here in San Diego. We use it for tuning and overall understanding what the heck is going on with the FIP😄. As you can see from the chart some cars were running lean or rich and then tuned correctly.
The take aways are:
- You want the overall curve shape in the graph. The curve shape can compress/extend, shift down/up depending on factors when you start taking the next tuning steps.
- Notice the low dip on chart toward the end? Thats the time that the airslide valve is still slightly open for that lean period I was taking about in the last post.
Regarding fuel flow, I believe it's ~1 liters in 15 seconds? Someone please check my memory🤣
When I did the test I did it right before FIP. I think I just read a couple of weeks ago (again check my memory 😄) it was also good to test flow at the return line to the tank.
More tests/info can never hurt😄
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Now that graph makes sense ... I saw it before and didn't really get it. I do have an old Bosch CompacTest (MOT 350 with the CO/CO2/HC analyser and MOT 401)... No idea how to use it but I'll do some research tonight. I'm sure it will help get the old girl purring again.
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That's exactly what I needed to know MrFatBoy. I was thinking that a cool running car is also a good thing too!
I still have not measured the fuel flow. Is it recommended to use a flow meter for this or simply disconnect the fuel line and collect the fuel over a specified time? Is this done at the return hose near the fuel pump?
Thanks
I think the simplest recommended test is to measure flow at the end of return line. Up to a litre in 15 seconds. Let the fuel pump warm up a bit. If you are 0.6-0.7l - it is already a low flow.
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Hi Pawel
Are you just running it into a container or do you have a flow meter set up?
Thanks!
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Just to container. Since I am not a mechanic, I do not even have this kind of tools.
I did this test when I was looking for clogged spot in my fuel delivery system. End of return line is giving full picture and is easy to access even for weekend mechanic like me - either the tank or at the T connector (late cars) if you have it.
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I've finally got the air shutting off through the WRD ... and the car stalls. I assume that the WRD has not been set properly for years as it had only 0.2mm of shims in there and that's not even enough for a new thermostat to turn off ... so I also assume this car has been "tuned" in the warm up state and as I mentioned before it blows loads of petrol smoke.
I can keep it going if I press on the throttle but it dies as soon as I release it making it a little hard to do the split linkage test.
Is there a starting point of the BC and a number of clicks that I should be counting on the FIP (eg 20 clicks back from all the way in) and go from there? I've got the BC loose and I'm still struggling to find a position for it to keep the idle going when warm.
Or is there a technique?!
Thanks!!
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I have a total of .080" worth of shims under my BC if that helps. Maybe that is a good starting point? You can use a rubber hose and jam it between the BC and the WRD to keep the BC from turning during a test drive.
Is it possible the idle speed is set too low (too little fuel and air) when the WRD air shuts off? If the WRD was previously sucking air, that means that it was also injecting more fuel. The two happen jointly and that ratio cannot be changed. More fuel and more air translate into a higher idle speed.
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So the engine runs when warming up and when warmed up it dies if you do not press the linkage? And it is producing lots of smoke when working? That would suggest it is too rich.
You can also split the linkage, keep it down holding both levers together by hand and with the other hand press or release one of them.
How much of shims do you have under the BC? More than what Wallace is saying? If yes - it is rich.
I started from 2mm of shims under the BC - it was advised to supposedly be close to starting point. It worked for me.
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It is possible to crank the car with the key and operate the throttle linkage directly with your foot by cocking your leg over the wing (fender)! This gets you enough RPM to quickly change from foot to hand and so keep it running while you make adjustments!
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Could you make and post a short film to show us how to do that?
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Here is an old post how to set up remote starter
https://www.sl113.org/forums/index.php?topic=16067.0
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If you do not have automatic, you can use pin 86 in cold start relay and an impulse switch. So: run the wire from + on battery (I did it with the fuse) to the impulse switch and from switch to pin 86 on cold start relay. Ignition on and engine will crank when you press the switch. Stop cranking when release the switch. Switch must be impulse one - connects only when you hold it, does not stay switched on when released.
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Today was a good day. The car is running really well but I feel that you might tell me that it will still be too rich.
I started by getting the car warm which was an effort in itself ... basically getting a mixture that allowed me to drive the car (it was stalling whenever I took my food off the accelerator.
I then adjusted the BC so that at higher revs the split linkage test was "normal".
Then adjusted the FIP thumbscrew for idle.
It's now idling at 800 ish. It's a little lower when its not fully warm but I don't know what it will be like after a full cool down over night. If it's idling too low during warm-up I'll add an oval shim to the WRD.
The car occasionally stalls when I stop quickly ... which I think I adjust the linkage dampener dashpot to get right?
The car drives beautifully and I don't think has run this way in many years. My only concern is that the BC has got 5mm of shims under it and this is way off the starting point of 2mm. But it's also the wrong FIP for the car (it's one for a 250SL) so this may account for that.
I'll get it all more accurate when I get the Bosch CompacTest up and running (currently translating the German instructions into English).
I'm taking it for a couple of hour drive tonight so I'll see what the plugs look like after this ...
BTW my technique for starting the car is window down, reach in and start the car and use a 1x1 inch block of wood on the venturi rod. Works well but I sometimes lose it when I swap to the other side of the car. Probably not as easy on a LHD car ...
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Really old thread, so here's hoping...
How do you turn/remove the compensator? My car is a '66 230sl and runs far too rich. I think I can feel shims underneath, so if I want it to lean up a bit then I need to remove a shim or two... am I reading that right?
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Under the round can, there is a hex for a wrench. I can't remember what size but maybe 19mm? Use that to loosen the can.
You say far too rich. What engine RPMs is that at? The compensator will more or less adjust the mixture at all rpm ranges. You first need to determine at what RPMs it is rich. If just at idle, It is possible to adjust the mixture at idle alone. But what ever you do, always make notes for what changes you do so you can always go back to where you were.
Yes, remove BC shims to lean. But be advised this adjustment is VERY sensitive. .003" shims can make a significant difference. Ultimately, this is more of a temporary fix. You should change the setting screws in the pump to be proper. But because that can be a daunting task and not for the faint of heart, most stick with the BC adjustment.
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The early compensators were 19mm the later are 22mm. The shims are 14mm I.D.
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Idle /mixture /ignition problems can be easyly identified with a so called "Gunson Colortune". Just Google for it or watch some available Youtube video's.
In short : It is a kind of transparent sparkplug replacement which makes it possible to peer into a cylinder with a running engine and observe the sparking and the combustion process . The color of the combustion process ( hence the name "Colortune") gives you a lot of information wheather your engine is running rich or lean in realtime conditions.
It makes fuel/air adjustments a piece of cake and avoids fumbling with split linkages at especially higher rpm's .
It helped me troubleshooting my poor running engine and is now one of my favorite tuning tools.
Our engines have 14 mm size sparkplugs. keep that in mind before ordering.
I am not a vendor , just regard it as a tip !
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ROSCH
Great tip RE GUNSON Colortune spark plug tool. I have found this tool on Amazon.com….14mm plug size. My car is in a different country right now so I can’t measure . Q? What size are our plugs pls? (1970 280 SL). I’d like to order so this tool is there when I get home to my car.
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Our engines have sparkplugs with 14 mm thread.