1967 250S Weber conversion?
 

Has anyone done this? Is there really an advantage to converting them? My carbs are out of adjustment and before I start investing a lot of cash, I'm wondering if it's better to just get Weber carbs.

Are they a direct replacement? I saw them listed here:
http://www.alamomotorsports.com/weber/mercedes_carb.html
They web site says they come pre-adjusted. I'm a bit leery of trying to work on the Zenith carbs I have.

So $840 is not a lot of cash compared to tuning the zeniths?

I run zeniths on my 72 250. I'm very happy with them I don't find it hard to tune them. Manual has all the steps you need. Unless your carbs are warped ( & even then) you should be able to tune them pretty easily.

It is a bit of change but my time is worth money as well. The problem is that I don't know where I'm starting from initially since I just got the car. I still have to get a manual. I've just heard a lot of problems with the Zeniths compared to the Webers. I don't want to put in all this work then wind up having to replace them anyway. I'm a pretty good 'shade tree' mechanic but I've never had to deal with carburetors until now.

Yeah my time is worth money as well, but if I didn't enjoy tinkering with these old beasts then I would have bought a Toyota.

It's really not that hard, and you'll have to do this with the webers anyhow. I know they say it's pre-adjusted, but they have no way of knowing if all your valves are adjusted properly or there is a different compression ratio between cylinders or anything else that will throw off the adjustments. Here is a online zenith manual

http://www.jaimekop.com/CarbManual/

You first need to set your timing and idle speed. Idle speed is done by the adjuster located on the back of the carb.

Separate the link from the front to back.

Then you'll need to set the mixture screws. I like to use a vacuum guage and get the maxumim vacuum.

Then you'll need a sync tool like a unisync or the jc whitney sync tool and an adapter. You can buy one or sacrifice a plastic ziplock container and make the adapter.

Go back & forth and adjust the idle speed nuts until they are sucking the same amount of air.

Re connect the links and make sure the lenght is correct. If the RPMs jump up or one carb is sucking in more air than the other, you'll need to re-adjust your links

Turn off the engine, set the fast idle ( move the linkage back and close the choke ) start teh engine and measure the gap as the engine is running. It should be 2.2 mm. If not then use the aduster located on top of the auto choke housing.

That's it. That's all.

BAM. Exactly what I need to tune the Zeniths on my 280S. Directions...

Thanks!

Well, once you get old enough to realize your time is worth money the equation changes.....

For me, it's therapy now, rather than economic....

That said, drove my Weber equipped 71 250C into work today. I cannot say enough about the transformation these carbs had on the car.

I love them! Once dialed in, they work seamlessly. Car starts immediately when cold (no need to even pump the throttle), settles into a buttery idle, electric chokes pull off automatically and no stutter, stumble or hesitation when either hot or cold.

Maybe not original, but you cannot tell once the air cleaner is on.

I remember spending hours in the early seventies screwing around with the twin Solexes on my 190SL, and finally biting the bullet for a pair of Weber 40DCOEs. Same transformation, that 190SL ceased to have any carb problems or need for periodic tweaking and ran great for 6 more years until sold. Probably ran great for many years thereafter, but I lost track of the car a few years later.

If the cash outlay is not a problem, you will not regret the modification.

Jim

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