Where to start? - 1971 250 w114 m130 zenith carbs - Mercedes-Benz Forum

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post #1 of 138 (permalink) Old 03-07-2014, 10:16 AM Thread Starter
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Where to start? - 1971 250 w114 m130 zenith carbs

I got the car running by gapping and cleaning the points, cleaning the distributor cap and rotor and the plugs too. Not knowing if this car is worth the effort, I'm trying to minimize costs and not replace everything as a precaution, but advice is needed on where I should start.

Rotted out rear exhaust.
Rotted out rockers.
Runs rich and fuel disappears quickly.
Spark feels weak.

Points and plugs on the way. In an effort to not waste money, even though it looks like the cap and rotor have some blackness, I've decided not to spend the $45 on the cap and rotor for now.

I should read the zenith carb manuals, but also have received a recommendation to clean out the fuel tank.

The power steering appears to have a pretty significant leak, so bad that it probably isn't worth pouring fluid in the reservoir to fill it up.

I know fluid changes are wise for any old car, and the only record of an oil change was 2 years and 2200 miles ago. But the radiator has sweat marks and the seller admitted filling the radiator three days before my purchase. I'm thinking oil and coolant are the least of my concerns and not worth the money (as long as they are topped off).

If I can get the car running right, sparking consistently and not fouling the plugs, not gushing fluids, then maybe it will be time to "do it right". But I feel I'm a ways from that point.

Does anyone have the "textbook" for bringing back the hunker on a shoestring budget?

Thank you for the advice!

This is my second thread I've created here, and here is the first in case you want to see any pics of videos of the car in question: http://www.benzworld.org/forums/show....php?t=1922049

(I expect people to see that thread and decide it is too long to read it all, so I created this one.)

Edit:
Replacing the points did not have an immediate effect. Plugs next. Then to choose between tank and carbs.

Edit:
I discovered why the old points were fried when if pulled them out. Someone has bypassed the resistors in the ignition setup and apparently connected the coil directly to the points. My new $12 points are fried. I will post pics in the original thread. Time to research HotSpark I guess.





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Last edited by Fonzi; 03-07-2014 at 10:48 PM.
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post #2 of 138 (permalink) Old 03-08-2014, 10:59 AM
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get your ignition working correctly first, then you can adjust the carbs as needed. do adjustments in correct order as listed in manual.

fuel tank filter is easy. if you dont have an allen that size, weld a bolt with head that size to a pipe. drain gas before doing so. blow line out towards tank.

change fluids and stop major leaks with new/rebuilt hoses. try one of the radiator stop leak products, they will work for a while. ever seen the put a raw egg in to do it?

How to Seal a Leaking Radiator: 6 Steps - wikiHow

exhaust is sort of a safety issue so I would do that.

scrub interior a lot

then have fun learning welding, It's really not all that hard, just takes practice.
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post #3 of 138 (permalink) Old 03-08-2014, 01:55 PM Thread Starter
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Where to start? - 1971 250 w114 m130 zenith carbs

Thank you!

1-spark
2-safety related items / leaks (brakes, power steering, exhaust, fuel, etc)
3-carbs

Maybe I will get some downspouts or dryer vent material from Home Depot to slide over the exhaust holes. :rofl:

Edit: I may not have to worry about the carbs too much after all. I'm not sure, but I don't smell fuel now that I got the spark issue cleared up. Returned wiring to stock w switchgear and borrowed coil from my 1978 450slc 5.0. Running well all but the fast gas pedal smash.

http://youtu.be/HetbkBh1dWY

http://youtu.be/41cIUO1doSg






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Last edited by Fonzi; 03-13-2014 at 01:32 PM.
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post #4 of 138 (permalink) Old 01-14-2015, 06:22 PM Thread Starter
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So. The above sedan has gone to a good home, and now I'm working on another car with the same carbs and engine. I'm now researching how to remove and clean the carbs. I found tonight that today's fuel looks like a real mess for carbuerators. This video doesn't do a very good job of showing the stringy spider webs that the fuel residue was making in my plastic cup. There were really sticky long strings. Sure, it's winter fuel and 30 degrees F (near the high, so the fuel could actually be colder) when I make the video.

http://youtu.be/NYaz4EvQ6sM

But removing the carbs and cleaning them on this car is definitely the next step.

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post #5 of 138 (permalink) Old 01-15-2015, 11:34 AM Thread Starter
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Ok. I think the above video is actually the fuel dissolving the solo cup. Sorry about that false alarm.

Still, I took the carbs off. It was my first time. Here's what I remember doing:

Fails:
- crows foot on a ratchet. Didn't fit.
- trying to get wrenches on inside bolts with valve cover on.
- doing this without the blue rubber gloves on. Too much filth and hand washing.
- open ended or 6-point wrenches.

Success:

- disconnect fuel lines and twist out of the way.

- carefully remove the linkages, wiring, and vacuum lines.

- remove valve cover: disconnect brake booster vacuum line and twist out of way. Disconnect smaller vacuum line. Remove three small bolts in the cover top. Pull it off. Easy peasey.

- use enclose 12-point wrench. Shorter the better. Fortunately I had recently bought a set that was still in the packaging. Most of my nuts were 12mm. For some reason the front inside was 13mm, which I guess means someone lost an original.

- I took off the front first. I think it provided more room to reach the rear one.

- carefully dump fuel in the carbs into a bucket.

Where to start? - 1971 250 w114 m130 zenith carbs-imageuploadedbyautoguide1421346813.592132.jpg


Maybe I will post pics of the insides of the carbs later.

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post #6 of 138 (permalink) Old 01-15-2015, 01:07 PM Thread Starter
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So I realize this is not the perfect thread for a carb cleaning and investigation thread (because it started with one if my cars and switched to another), but I'm moving forward with it instead of creating a new thread.

There are some question I have that I will be looking to answer:

1) what is the main offender in these carbs? Why will the car only run on full throttle with tons of fuel poured in the carb?

2) when I do the above, where is the fuel all going? I to the engine, or back via the return line?

3) why is there only a return line on the front carb? Is the fuel able to return from the rear carb via the supply line to the front carb bowl?

4) what is an accelerator pump, and how does it work? The white sedan seemed to have an accelerator pump issue, and the previous owner of this blue coupe said he thinks it had accelerator pump issues.

5) later, how do the heat risers work? And are the ones on this car stuck?

6) how can a novice clean and put a zenith carb back together on a serious budget. Is it even necessary to purchase a rebuild kit? (I guess it would be worth me buying a set as the carbs will be worth more if properly rebuilt.)

7) is there an amount of pressure or flow that is required from the fuel pump that can be tested? (I am not confident that my problem is not a faulty fuel pump, but I do doubt that is the problem. It will be good to eliminate this as a possible problem. I do have a spare new-in-box pump.)

There may be more questions, but this will be a good start in my opinion.
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post #7 of 138 (permalink) Old 01-15-2015, 01:25 PM
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1) what is the main offender in these carbs? Why will the car only run on full throttle with tons of fuel poured in the carb?

A. there are a bunch of tiny jets and orifices inside that get plugged up. It only runs on gas dump now because they are all plugged up. Be diligent about putting them back in the same place, some look similar but arent. there are markings on them.

2) when I do the above, where is the fuel all going? I to the engine, or back via the return line?

A. just straight into the intake manifold.

3) why is there only a return line on the front carb? Is the fuel able to return from the rear carb via the supply line to the front carb bowl?

A. That whole thing is to prevent dieseling when the engine is turned off. When working properly, which most dont, the valve on the front shuts off fuel flow. many rig past this, as the valve is unobtainium as is the diaphragm inside, unless you are like me and make my own.

4) what is an accelerator pump, and how does it work? The white sedan seemed to have an accelerator pump issue, and the previous owner of this blue coupe said he thinks it had accelerator pump issues.

A. easily visible on right side of carb, squirts extra gas when you first hit the throttle. work the linkage and you should see gas squirt down the throat.

5) later, how do the heat risers work? And are the ones on this car stuck?

A. very likely stuck. we had a great thread here last year about them, to determine correct position closed. I wired mine shut, or you will get vapor lock in the summer. some people even weld them shut. When operating correctly the direct hot exhaust gas to the base of carb for quicker warm up. They are operated by bi-metal coil spring that is probably long gone from yours.

6) how can a novice clean and put a zenith carb back together on a serious budget. Is it even necessary to purchase a rebuild kit? (I guess it would be worth me buying a set as the carbs will be worth more if properly rebuilt.)

A. depending on how careful you are you may be able to take apart and still use old gaskets. be very careful separating each section. Get a couple of cans carb cleaner and do each carb separately. Again write down what size jet came form where.

7) is there an amount of pressure or flow that is required from the fuel pump that can be tested? (I am not confident that my problem is not a faulty fuel pump, but I do doubt that is the problem. It will be good to eliminate this as a possible problem. I do have a spare new-in-box pump.)

A. dont know for sure, but probably only 3-4 psi.

There may be more questions, but this will be a good start in my opinion.[/QUOTE]
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post #8 of 138 (permalink) Old 01-15-2015, 01:36 PM Thread Starter
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Wow. Thanks Rumb. I was expecting to learn from experience, not spoon-feeding, but I like to eat information any way it can get it. So thank you!
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post #9 of 138 (permalink) Old 01-15-2015, 06:37 PM
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Fonzi, here is a link to the heat riser thread.

http://www.benzworld.org/forums/vint...help-pick.html
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post #10 of 138 (permalink) Old 01-15-2015, 11:56 PM Thread Starter
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Quote:
Originally Posted by Luna Gaudi's 72 250 View Post
Fonzi, here is a link to the heat riser thread.

http://www.benzworld.org/forums/vint...help-pick.html

Thanks Luna! I will snap some pics of the heat riser stuff in the daylight tomorrow.

Tonight as I was cleaning up my shed to make a workspace to disassemble these carbs, I realized that I really don't know how to split these carbs. I also see some gasket sealant squeezing out on the carb that makes me wonder how I'm going to split these carbs.

I think these carbs have been off before as there was a 13 mm nut on one stud while all others were 12 mm. So in guessing the previous rebuilder used something like the Indian Head Gasket sealant or similar. Pics tomorrow.

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