Chuck, this is a thread about carbs and getting a car to run. What were YOU thinking about?

-CTH

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- cth350@gmail.com
http://www.111lakeside.com/

Chuck..

I'm so GLAD to hear that you're STRAIGHT!!

Now...do I want to make this ROD get BIG or stay SMALL??? Do I need a tool for this or can I just use my hands??

~Christy

OK - Just for grins I will jump back into this one.

Christy, when I got my 250C I did not have a clue as to how the carbs worked so I did a lot of what you did, read and experiment. My car was running but not well. Once I tended to the ignition items I started on the carbs. After many trials and errors (and these were the Zeinths - not the Webbers I replaced them with) here is what I ended up doing to get them balanced.

Oh, by the way, don't worry about the missing vent valve thingie - I didn't have one on one of my carbs either and once I got everything setup it didn't make a whit of difference. Same for the fuel bypass valve.

I removed the linkage between the carbs - yes you have to do this. I took my adjustors off (the ones that couple the throttle actuator arm to the base plate) and set the star wheels in the middle then replaced them. I decided I needed to have as much adjustment hi or lo since I didn't know what else to do. Then I adjusted the idle stop screws (verticle screw down from the top plate with the lock nut on the bottom) so that each had the same number of threads exposed below the lock nut. I don't remember how many there were. I do remember that looking down the PRIMARY carb barrel on each carb that the plates were open a little. I could get the shaft of a 1/32" drill bit between the plate and side of the carb. I started the car and as I remember it didn't idle at all but slowly died. I screwed down the idle stop screws 1/4 turn on each carb (NOT the adjustment thingie) and tried again. I think that was enough (or maybe I had to do another 1/8 of a turn - don't totally remember) to get a sustained idle. Then I put my meter on the carbs and worked to get them balanced. I got them close by using the idle stop screws rather than the linkage adjustment thingie. When they were close I fine adjusted with the linkage adjustments and set the idle speed that way. Had to play a little with the mixture screws too, so it is a balancing act. I set my idle to 900 (yes, I have an automatic) and set the clearance between the dashpot to throttle on the rear carb to .003" (a piece of index card will work too). As idle speed drops the dashpot will extend and pick it back up some. It also keeps the throttle from slamming shut when you lift your foot at speed. Oh yes, I think I started with both idle mixture screws 2 1/2 turns OUT. I may have read that somewhere too.

Then I replaced the carb linkage rod adjusted so it did not change the idle speed. I drove my car that way for a little over 6 months and then go the Webbers. The car ran OK it was just not as smooth as I thought it could be and it always had an off-idle lag and the secondaries seemed to always open later than I thought they should. Plus it was a real b**** to adjust the chokes going from 100+ summers to 15-25 in the winter. I like to run less choke in the summer around here.

Anyhow, once you have successfully gotten them balanced, you will not ever forget how again. Like riding a bicycle - well sort of.

Good luck.

Dan

__________________
Dan Taylor/ Tulsa, OK MBCA
'84 300D/'90 Jaguar XJ6/XJ40

Dan...great info!! Thanks!

Here's what it is...

Ok...I may not have done every step...but....I got 2 carbs to be doing the same thing...the ball on the unisyn goes to the same place on both carbs and the car doesn't die upon placement of the device...BUT...the car is now idling at 1000 rpms....which is ok by me...BUT in GEAR it's STILL at 600 rpms...isn't 600 too low???

I'm totally disorganized and can't find a book and have no time to check my CD...does anyone know what the rpms should be IN GEAR??

It seems to me that the carbs are synced...but then again, I don't know what I'm doing and didn't touch the ROD!!!!!!(that poor rod!)..

~Christy

Looks like 650-700 by haynes, for what thats worth. Sounds like you're not far off now.

Mark

Christy,

Congratulations !!!

The first bit of bad news, is that you MUST remove that rod between the carbs to balance them. But, you are indeed correct, that you're on the right road to well-ville. Pull the rod and see how far off you are.

The other bit of bad news, is that the road is a bit longer than you think.

There are TWO adjustments that you have to make to get two different things to get all balanced out.

You might well be in a good enough condition to drive it now, but you're not out of the woods, so be conservative on the road.

To get a sense of how far off you are, do the ball-point pen test. Use a pen tip to block off that little air bore on the primary and watch the RPM drop-off. Your carbs are balanced when BOTH the guage test shows they match AND the drop-off is the same from the ball-point pen test.

(Sorry ).

-CTH

__________________
- cth350@gmail.com
http://www.111lakeside.com/

First off......thanks ALOT for bursting my happy little bubble.....I was ready to float off into the world.....*sigh*

Ok...I'm having some problems as you ALL knew I would. Ok...the top choke flap on the rear carb seems to be sticking. When I start the car, it's idle is around 500-600 rpms...so IF I can get it to hang on, I jump out and BARELY touch that flap on the rear carb and WATCH OUT!!!!!!!! The rpms JUMP up OFF of the ricter scale!!! (to around 2000 rpm, guessing)

NOW I know that sometimes the front carbs gets warmer faster than the rear and it tend to open a bit more, faster. BUT for the most part, these flaps SHOULD BE in the same place..right??

So..let's review....at touch of air to the rear carb raises the rpms DRASTICALLY!!!! Why?????

AND go ahead and tell me that they're NOT balanced....

~Christy

Guys!!

What the heck do I do with this ROD?????? I removed it and it is totally crustified to be NON-adjustable!!!!

Are you saying that I should try to balance these carbs with this rod OFF??? THEN put it back on and it shouldn't really MOVE anything??(or change idle??)

I'm not trying to be dumb.....really!

~Christy

Christy,

Good morning! Sorry to spoil your AM.

The choke flaps actually do behave a bit differently in Benz's infinite wisdom. BUT, eventually, both warm up (in under 5 minutes) and stand erect. Or at least that's what's supposed to happen WITHOUT the gentil touch of the driver's loving hand.

Is the electrical lead to the rear cover still attached? That would sure mess it up. You can ignore it for now if you want by using a twist-tie between the flap and the cover plate. By wedging it in there the flap won't move. Be sure to secure the other end of the twist-tie to the rod on the flap so that it doesn't get injested into the motor.

-CTH

__________________
- cth350@gmail.com
http://www.111lakeside.com/

Christy,

The rod is a bit crusty. A soak in WD-40 should loosen it a bit. Some MMO will keep it moving.

If you don't remove the rod, then adjustments to one carb also affect the other. Kinda like always living with your big sister. You never get to do something on your own.

At each end of the rod is the metal cap. The cap only turns when the jam nut that's up against it is pushed away first.

To complicate things take a good look at the threads on each end of the rod. That rod is just like those little spring loaded ones. One side of it is threaded backwards. If turning the jam nut one way doesn't work, go the other way.

-CTH

PS. My "n" key hasn't been working for the past 24 hours. Typing these messages has been loads of fun.

__________________
- cth350@gmail.com
http://www.111lakeside.com/

Here's the biggest question, at hand.....do I try to do adjustments TO the spring loaded vertical do-hicky with the ROD OFF??? OR do I play with the rod a bit FIRST (with everything in tact?)....

What do I do first??

I'm LOST!!!!!!!!

~Christy

with the long rod off, adjust the carbs.

THEN, put the long rod back on such that it fits nicely without forcing the throttles to move.

The idea, is that once the carbs are balanced, BOTH throttles move the same amount at the same time.

-CTH

__________________
- cth350@gmail.com
http://www.111lakeside.com/

Hi!!

I figured out some major stuff today..with all of your help, of course!

One problem was when I opened up that top flap on the rear carb, the car would rev totally out!! It ends up, that ALL of the moving parts were STIFF and were getting STUCK! It made a serious difference.

The rod issue is under control too. I took it off and lubed it up. I went on to try to balance the carbs with it OFF and then made it the right size and put it back on! Now both carbs do the same thing at the same time! (<-- that's the statement that made it all CLICK with me...thanks CTH!)

So...now the car idles around 1000 rpms..IN GEAR it is still a HAIR below 600 rpms. Is it possible to change the rpms IN GEAR?? Do I need to?? Or is 600 ok??

Also...the big NUT thingy off of the vacuum thingy (!) off of the rear carb is a thick HAIR from touching the linkage, which seems to be about right...let me know! An index card would fit right between those parts....maybe even 3 index cards...

So....I can't wait to drive it! Should I try??? What do you guys think?? The car seems really stable....Although, I could be wrong. That I'll find out when I try to TURN the wheel I guess.

Btw...is the power steering resevoir one of those white jugs under the hood??

~Christy

The power steering resevoir is the black can with the little "wing nut" on top. You should be able to screw it on and off by hand w/o a wrench.

However, the last guy to tighten it may not have known that and over tightened it. A basic pair of pliers will get it off. Tighten it by hand.

GO for it. Take it for a drive. Start with a very short one, just make right out of the drive way and go to the end of the block and back. If you can make it w/o stalling, you can try around the block, but not that big hill, until you can make it around the rest of the neighborhood.

You go girl.

-CTH

__________________
- cth350@gmail.com
http://www.111lakeside.com/

Guys!

If I get the carbs adjusted wonderfully when the car is HOT....it's NOT right when the car is COLD!!! What is that???

For example...I had both carbs doing the same thing yesterday. The idle was around 1000rpms. I thought I was all set!

When I got in it today....the idle was barely 600 rpms, cold. I let it warm up and as it did, the rpms all of a sudden jumped to 1200rpm + all on it's own!!! (Poltergeist!!!)

So....Once it was a full operating temperature, I got everything just so again. I was ready to go for a test drive and it STALLED when I turned the wheel again!!! So I checked that power steering resevoir and found it to be about 1/4 inch from the rim. FULL.

So....what's the problem??? dashPOT???? Should I try to make the nut lower??????

May I ask this weird question again....can I raise the rpms when the car is IN GEAR??? Maybe if it was higher it wouldn't STALL???

I don't know!!!

~Christy