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  #1  
Old 04-21-2016, 09:52 AM
meltedpanda's Avatar
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Solex 34 PCIB

Thanks to all that I have received info from but still having trouble finding specific information on the PCIB solex units on my car ( 62 220b). One issue in particular is the on the back carb at full throttle ( manually opened the linkage all the way) the butterfly does not appear to open all the way , I am not sure if that is normal. I do see a way , I think to adjust it but want to hear from anyone with some insight into basic set up and tolerances , thanks in advance!

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Ron
2015 Porsche Cayman - Elizabeth
2011 Porsche Cayman - Bond,James Bond
Sadly MERCEDESLESS - ALways LOOKING !
99 E320 THE Queen Mary - SOLD
62 220b - Dolly - Finally my Finny! Sadly SOLD
72 450SL, Pearl-SOLD
16 F350 6.7 Diesel -THOR
19 BMW X5 - Heaven on Wheels
14 38HP John Deere 3038E Tractor -Mean Green
84 300SD, Benjamin -SOLD
71 220 - W115-Libby ( my first love) -SOLD
73 280 - W114 "Organspende" Rest in Peace
81 380 SL - Rest in Peace
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  #2  
Old 04-21-2016, 01:24 PM
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Here are some basics I've picked up in my experience tuning dual carb setups.

1 - Both carbs should stay closed at idle with the linkage disconnected. The linkage should not hold or push the carbs closed at idle. I looked at the setup in W115 with dual Solex carbs. There's a coil spring for each carb that connects between the throttle lever and the manifold, thus providing this function. Maybe your car is basically the same.

2 - Both carbs should be setup for proper idle with linkage disconnected. The process described by the book for W115 with Solex duals involves using a sync tool to measure air flow into the carbs and adjusting them to draw the same amount of air at the correct idle speed. There are workarounds for doing it without a sync tool but I won't go into them here in the interest of keeping things simple.

3 - Connect the linkage and adjust it so that it doesn't pull either carb open at idle. The point is to have the linkage start pulling both carbs open at exactly the same time. On the W115 dual Solex setup there is a short adjustable rod from each carb to a "angle relay lever", and then there is a longer adjustable rod that runs between the two angle relay levers. Maybe your setup is pretty much the same.

If there's play in the lever bushings and looseness in the ball-and-sockets on the rods/levers you can pretty much eliminate the effects by setting up the rods to take out that slack in the idle position. You are essentially pre-loading the linkage so it's primed to pull both carbs off-idle at precisely the same time while not having to take up linkage slack in the process. If you've got balls loose on the brackets you can remove the bracket and use a ball hammer to snug up the rivets. If you've got loose bushings between the levers and the posts they ride on replace them with new parts. I've used bronze USA car door hinge bushings to make that repair, too.

In your case it sounds like you could have a linkage adjustment issue causing the the front carb to reach max before the rear does, as if the front carb is getting pulled open before the rear one. I'd start with establishing balanced idle between the two carbs, and then get into the linkage adjustment. I'd start with the short rods at each carb having the same length and then using the adjustment on the long rod to cause both carbs to open at the same time. That should get you pretty much on the money for max throttle as well.

If the short rods at the carbs are different lengths the linkage can still be set to open off-idle at the same time but they will reach max at different times due to geometry issues caused by the different lengths of those short rods pulling between the relay and throttle levers.

Sorry about the lack of specifics for your car, but these general tips might help you dial it in.
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1973 220D, The Prodigal Benz
1974 240D

Last edited by gmog220d; 04-21-2016 at 01:35 PM.
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  #3  
Old 04-21-2016, 01:42 PM
meltedpanda's Avatar
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thanks, that is a bit more info than I had, I have the "closed situation " pretty good the back carb at full throttle m does not open all the way , I will have a look at the arm lengths as a possible cause
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Ron
2015 Porsche Cayman - Elizabeth
2011 Porsche Cayman - Bond,James Bond
Sadly MERCEDESLESS - ALways LOOKING !
99 E320 THE Queen Mary - SOLD
62 220b - Dolly - Finally my Finny! Sadly SOLD
72 450SL, Pearl-SOLD
16 F350 6.7 Diesel -THOR
19 BMW X5 - Heaven on Wheels
14 38HP John Deere 3038E Tractor -Mean Green
84 300SD, Benjamin -SOLD
71 220 - W115-Libby ( my first love) -SOLD
73 280 - W114 "Organspende" Rest in Peace
81 380 SL - Rest in Peace
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  #4  
Old 04-21-2016, 02:23 PM
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Right on. I'd guess that your car's rod for the front carb is shorter than the one for the rear. Make 'em the same and then adjust the long rod to synchronize off-idle open.

Hope it helps! Let us know what works, and if you have more difficulty.
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1973 220D, The Prodigal Benz
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  #5  
Old 04-21-2016, 08:33 PM
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idle mixture screws , about 1.5 to 2 turns out ? Idle screws just enough to open butterfly's?
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Ron
2015 Porsche Cayman - Elizabeth
2011 Porsche Cayman - Bond,James Bond
Sadly MERCEDESLESS - ALways LOOKING !
99 E320 THE Queen Mary - SOLD
62 220b - Dolly - Finally my Finny! Sadly SOLD
72 450SL, Pearl-SOLD
16 F350 6.7 Diesel -THOR
19 BMW X5 - Heaven on Wheels
14 38HP John Deere 3038E Tractor -Mean Green
84 300SD, Benjamin -SOLD
71 220 - W115-Libby ( my first love) -SOLD
73 280 - W114 "Organspende" Rest in Peace
81 380 SL - Rest in Peace
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  #6  
Old 04-21-2016, 10:10 PM
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1.5 - 2.0 turns out is a good starting place for the idle mixture screws. Just pick one and go from there.

Turn the idle screws out until they don't touch the stop. Turn them in 'til they just touch the stop, and then go in another 1 - 2 turns on both screws (this is general and not necessarily "by the book" for these carbs). Chances are you'll need to adjust idle more from there but that should be a good starting point. And it's pretty common for the carbs being set a little different from each other to achieve good balance at idle, but they should be pretty close given the same number of turns.

Some carbs are pre-set for idle by measuring the gap between the edge of the throttle plate and the venturi with a feeler gauge.

Do you have a sync tool for balancing the carbs at idle?
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1973 220D, The Prodigal Benz
1974 240D
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  #7  
Old 04-21-2016, 10:13 PM
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Thanks , no sync tool , but have seen them referenced . I will keep you all posted
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Ron
2015 Porsche Cayman - Elizabeth
2011 Porsche Cayman - Bond,James Bond
Sadly MERCEDESLESS - ALways LOOKING !
99 E320 THE Queen Mary - SOLD
62 220b - Dolly - Finally my Finny! Sadly SOLD
72 450SL, Pearl-SOLD
16 F350 6.7 Diesel -THOR
19 BMW X5 - Heaven on Wheels
14 38HP John Deere 3038E Tractor -Mean Green
84 300SD, Benjamin -SOLD
71 220 - W115-Libby ( my first love) -SOLD
73 280 - W114 "Organspende" Rest in Peace
81 380 SL - Rest in Peace
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  #8  
Old 04-21-2016, 10:36 PM
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If you need some tricks for balancing at idle without the sync tool let me know.
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1973 220D, The Prodigal Benz
1974 240D
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  #9  
Old 04-22-2016, 10:02 AM
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Ok , I was able , by getting the two short rods the same length and fiddling with the long rod connecting the two to not only get any tension off the linkage, but now the butterflys at full throttle look pretty much the same I set the other mixture screws as discussed . a few more minor adjustments on the point gap and I will fire her up. Hopeful for good or reasonable result. any balancing tricks are much appreciated , here or by PM. Thanks!

PS can the unisyn still be purchased /rented /begged for these carbs?
__________________
Ron
2015 Porsche Cayman - Elizabeth
2011 Porsche Cayman - Bond,James Bond
Sadly MERCEDESLESS - ALways LOOKING !
99 E320 THE Queen Mary - SOLD
62 220b - Dolly - Finally my Finny! Sadly SOLD
72 450SL, Pearl-SOLD
16 F350 6.7 Diesel -THOR
19 BMW X5 - Heaven on Wheels
14 38HP John Deere 3038E Tractor -Mean Green
84 300SD, Benjamin -SOLD
71 220 - W115-Libby ( my first love) -SOLD
73 280 - W114 "Organspende" Rest in Peace
81 380 SL - Rest in Peace

Last edited by meltedpanda; 04-22-2016 at 10:29 AM.
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  #10  
Old 04-22-2016, 12:00 PM
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Ron, PM me your address. You pay the shipping and I'll send you one to use.


Or:

http://www.ebay.com/itm/like/272204146878?lpid=82&chn=ps&ul_noapp=true

You'll need to replace the felt pad on the Ebay one. No big deal. You can get sheets of gasket material at any hardware store.
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  #11  
Old 04-22-2016, 12:17 PM
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Sweet! Be sure to check over the linkage function after the engine is warmed up. Expansion might not be an issue on a in-line engine, but it's worth verifying all the adjustments are good after it's been run a while.

I'm guessing your carbs have idle jets without cutoff solenoids, correct? Does each manifold have a vacuum port, both the same diameter, you can connect to? I think for the long term you'd be served by investing in your own Uni-Syn, a snail type synchrometer, or a electronic meter that reads manifold vacuum (the Cadillac of the options, IMHO). They make the job pretty easy.

Anyway, there are several things you can do. If you have cutoff solenoids on the idle jets you can run the engine at idle and disconnect each side's jet solenoid's power supply and note the drop in RPMs. The idea is to set the carbs so you get the same RPM drop off, while having good idle RPM when both carbs are connected. Works well assuming the engine will stay running with only half the cylinders firing. A dwell/tach meter can be handy doing it this way, but sometimes the engine's running too lumpy to get a good reading and you end up going more by ear.

Another method is to use a section of tubing inserted into each venturi to listen to the hiss of air being drawn in. The idea is to set the carbs so they hiss the same. Truly the old school method here.

If you've got identical diameter vacuum ports on both manifolds you can make a tool using clear tubing filled with a bit of ATF. The ATF stays in a low bend in the tubing and uses vacuum signal from each manifold to give an indication of balanced or imbalanced suction between the carbs. If the ATF is drawn more to one side you know that carb is pulling more. Search "carb balancing tool" and you'll find plans for many variations of this tool. Sometimes it is necessary to use an orifice in either end of the tubing to slow down the ATF's movement. If you like building your own tools this is an easy one to do and would serve you well.

There's also a cool electronic tool that reads off manifold vacuum. "CarbMate" and "Tecmate" are worth looking at. A friend of mine has one of these with a analog needle and I think it works great.

I really like the tools, homemade or other, that connect to both manifolds to give a more dynamic reading between both carbs at once.

There's a nice mixture of backwoods and more "together" options for you. Some web searching would add to the list, I'm sure.
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1973 220D, The Prodigal Benz
1974 240D

Last edited by gmog220d; 04-22-2016 at 12:27 PM.
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  #12  
Old 04-22-2016, 01:58 PM
meltedpanda's Avatar
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Great info. And thanks Mark. Since I plan on keeping this one I may just invest in one. Here is a picture of my carbs. Pretty basic set up ,no cutoff selenoids. It does have the return valve on the front carb. The picture shows the arm disconnected , decided to take a picture to make sure I knew where things went back I only have the vacuum drawing from the front carb



__________________
Ron
2015 Porsche Cayman - Elizabeth
2011 Porsche Cayman - Bond,James Bond
Sadly MERCEDESLESS - ALways LOOKING !
99 E320 THE Queen Mary - SOLD
62 220b - Dolly - Finally my Finny! Sadly SOLD
72 450SL, Pearl-SOLD
16 F350 6.7 Diesel -THOR
19 BMW X5 - Heaven on Wheels
14 38HP John Deere 3038E Tractor -Mean Green
84 300SD, Benjamin -SOLD
71 220 - W115-Libby ( my first love) -SOLD
73 280 - W114 "Organspende" Rest in Peace
81 380 SL - Rest in Peace
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  #13  
Old 04-22-2016, 02:55 PM
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Looks like your best option will be to use a Uni-Syn other similar tool. The Uni-Syn will fit the carb tops best, I think. Or the "hiss method" until you get a tool in hand. You might be surprised at how well you can hear the difference.

How are the throttle shaft bushings? If loose they can buggar up the idle tuning process because of the extra air leaking in and leaning out the mixture. Really loose bushings can also make adjusting the linkage a little tougher too.
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1973 220D, The Prodigal Benz
1974 240D
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  #14  
Old 04-23-2016, 10:05 PM
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everything seems pretty tight , I went to fire her up this afternoon but could not get her to catch, then I ran out of time ...again
I may have to back out the idle mix screws ?

And I ordered a uni syn thanks for the heads up!
__________________
Ron
2015 Porsche Cayman - Elizabeth
2011 Porsche Cayman - Bond,James Bond
Sadly MERCEDESLESS - ALways LOOKING !
99 E320 THE Queen Mary - SOLD
62 220b - Dolly - Finally my Finny! Sadly SOLD
72 450SL, Pearl-SOLD
16 F350 6.7 Diesel -THOR
19 BMW X5 - Heaven on Wheels
14 38HP John Deere 3038E Tractor -Mean Green
84 300SD, Benjamin -SOLD
71 220 - W115-Libby ( my first love) -SOLD
73 280 - W114 "Organspende" Rest in Peace
81 380 SL - Rest in Peace
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  #15  
Old 04-24-2016, 10:06 AM
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Posts: 947
You'll be glad you ordered the Uni-Syn.

You might move the throttles to make the accel. pumps squirt a little gas in each carb before messing with the adjustments. It wouldn't hurt to connect the linkage so you can use the throttle/pedal to get it going and warmed up. Once warmed up you'll be able to better gauge what you need to do with the screws.

If it's obviously not getting enough gas for idle and you can't get it to run on its own go ahead and turn in the idle speed screws to increase speed, and maybe go ahead and open up the mixture screws a little if it's still struggling to get gas. Be sure to make the same adjustment to both carbs - whatever you do to one do to the other. You might have to play around with them for a bit before getting it to idle. Let your intuition guide you on which screws to turn, idle speed or mixture, in or out.

Once you get it to idle reasonably on its own fully warmed up disconnect the linkage and then do the carb fine tuning with your new Uni-Syn. At this point it shouldn't take too much fiddling with the screws to get them balanced. You may need to make adjustments to one carb without touching the other, and that's OK so long as you're not making a "gross" adjustment of either speed or mixture. It's all a balancing act, and again, let your intuition guide you.

Once you've got them balanced at idle go back to the linkage and make whatever small adjustments you need to compensate for any minor differences between the carbs you had to make and you should be set.

And once you've come this far it wouldn't hurt to think about using your Uni-Syn to check balance at higher RPMs, and possibly fine tuning your linkage some more. You can adjust the Uni-Syn's sensitivity range to get readings at higher air flow rates. If you find that one carb begins pulling more at mid and high RPMs then you can think about making adjustments to the small push-rods between the relay and throttle levers to compensate. This is where you might end up making the small rods slightly different lengths to dial in carb balance at various throttle positions.

Have fun!

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1973 220D, The Prodigal Benz
1974 240D

Last edited by gmog220d; 04-24-2016 at 10:18 AM.
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