Source for Zenith 35/40 parts eg jets

1965 - 1972: 250S, 250SE, 300SEb, 280S, 280SE, 280SEL, 280SE 3.5, 280SEL 3.5, 280SE 4.5, 280SEL 4.5, 300SEL, 300SEL 6.3, 300SEL 3.5, 300SEL 4.5
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Tazzieman
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Model you own: w108

Source for Zenith 35/40 parts eg jets

Post by Tazzieman » Wed 02 Aug, 2017 8:28 pm

Can anyone point me in the direction of a supplier?
I have rebuilt one set of 35/40 carbs on one of my W108s but wish to try replacing the jets to try and improve running.
Thanks , Paul

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starman61
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Re: Source for Zenith 35/40 parts eg jets

Post by starman61 » Wed 02 Aug, 2017 10:46 pm

Try these places:

https://classiccarbs.com.au/index.php?_ ... rts&page=2

http://zenithcarb.co.uk/jets.html

e-bay also has jet kits from time to time.

You may also wish to check with the forum sponsor and also do a search in the white pages.

Kind Regards

Bill
'65 W111 220SB
'72 W108 280SE 3.5
'79 R107 450SL
'84 W126 380SEC
'98 R129 SL280
'10 Sprinter 318CDI

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Tazzieman
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Re: Source for Zenith 35/40 parts eg jets

Post by Tazzieman » Thu 03 Aug, 2017 9:36 pm

Thanks Bill
The classic carbs guy forwarded me onto another guy in Melbourne who's searching for me. I'll report back.

W108-1967 250S
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Re: Source for Zenith 35/40 parts eg jets

Post by W108-1967 250S » Sun 06 Aug, 2017 1:12 pm

Re built my carbs a while back but still need to run engine, on this ongoing project. But I got a re-build kit from a USA supplier. The sponsor should also be able to source a kit I'm sure. Posted the re-build on the site with some pics.

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Tazzieman
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Re: Source for Zenith 35/40 parts eg jets

Post by Tazzieman » Sun 06 Aug, 2017 3:10 pm

My rebuild kits were pretty comprehensive , but didn't include the jets.

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Mercmad
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Re: Source for Zenith 35/40 parts eg jets

Post by Mercmad » Mon 07 Aug, 2017 7:54 am

The only way to do it actually is to get a set of gas fitters jet drills. Not cheap, they run to $300 usually, then solder the jet and drill it to the size you need. But as Daimler got the jet sizes spot on, you really won't make the car run better by trying to out engineer them. :book: :read2: :laughing6:

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Tazzieman
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Re: Source for Zenith 35/40 parts eg jets

Post by Tazzieman » Mon 07 Aug, 2017 10:46 am

Mercmad wrote: But as Daimler got the jet sizes spot on, you really won't make the car run better by trying to out engineer them. :book: :read2: :laughing6:
You won't find any arguments form me there. But as they are a wear item , and other "surgeons" have clearly dicked with my carbs a little roughly shall we say , after getting them 90% of the way to run well in a cold climate I'm going to make the effort to get them as 100% as they can be. Given the inherently flawed nature of the setup???
It would be easy to drop in some Webers , but I don't look for easy solutions and like to keep my old cars as the maker intended. to preserve history as much as anything.

Now where can you point me to a source of synchroniser hoods that fit the 35/40s? The idle balance is pretty good , but not "100 %"
The yankee tupperware "solution" hasn't worked for me yet, in case anyone is wondering.

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Mercmad
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Re: Source for Zenith 35/40 parts eg jets

Post by Mercmad » Tue 08 Aug, 2017 8:48 am

Do you have a regualr carb synchronizer ? I have one of those curved plastic ones which works really well. The carbs are tuned with the air filter in place so the crankcase vent etc can be taken into account. So what you can do is get a spare air cleaner and cut the top open . weld in a ring (50 mm high )with a lid that has a hole suitable for seating the carb sychro device. You need two rings ,both with the lid and hole on top to mimic flow between the two. A tube from the crankcase vent to the manifold fitting is connected to the rings. you now have a device which should mimic the effect of being connected to the aircleaner .It's important as Zenith carbs, while they run without the aircleaner, have what is known as a "fuel stand off effect". .A cloud of fuel above the carb at speed . They designed to run with the aircleaner in place in other words. Mixture can only be checked with a C/O meter which most garages have or are supposed to have. With the carb sychro thing in place you can get a more accurate idea of how the carbs are running. Anyone who can get these carbs to run half way decently deserves a medal.

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Tazzieman
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Re: Source for Zenith 35/40 parts eg jets

Post by Tazzieman » Tue 08 Aug, 2017 11:16 pm

Well that makes a lot of sense; cheers for the tips. I do in fact have a spare air cleaner to modify. I can easily borrow a synch tool; I tried to make a sync hood before but couldn't get it quite right.

The carbs on both cars are running reasonably well , given their age and some unreplaced parts. So I figure I get a bronze medal at least :coffee2: Yesterday I adjusted the idle lifting switch on the auto one and ticked off another issue. It's good to pull these things apart and clean the grunge and see exactly how they work. Mine was smoking during adjustment and I found it was full of old oil that had leaked from fumes through the hardened O ring of the air filter- soiling the contact points.

Both carbs start pretty easily on cold mornings but do lack a little smoothness/pickup. Then again , I've never driven a car with brand new factory adjusted carbs, so not sure what the end point should/could be.
I can say I "don't have any trouble keeping up with modern traffic" in either city or hwy situations , except on hills. Fair enough, it's a really old car!

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Mercmad
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Re: Source for Zenith 35/40 parts eg jets

Post by Mercmad » Thu 10 Aug, 2017 9:16 am

If ther car starts on a cold tassie morning you are onto a winner! . Getting them to start properly is part of the struggle. I worked on them back in the 70's when the cars (BMW and Mercedes ) were still fairly new and low mileage and the buggers still gave trouble . The best idea is to get the valves adjusted properly and the ignition at 100% . To sort the ignition fit a set of pertronix things, their dealer is in melbourne so not too far from you . Pertronix don't work so well the original Mercedes plug leads so a set of carbon core leads will be required too (ugly as they are) . You may find the stumbling on acceleration is ignition and the lack of spark .

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Tazzieman
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Re: Source for Zenith 35/40 parts eg jets

Post by Tazzieman » Thu 10 Aug, 2017 9:27 am

I replaced all stock ignition components and have been meticulous about adjusting points , timing, choke gap etc to get the cold starts as good as possible. Valves were carefully adjusted.
The cars obviously start better if they haven't been sitting for days.
One set of carbs (grey car) hasn't been rebuilt yet. I've done one from a donor car but it's sitting in a box for now. I had one failure to proceed up our steep hill in the white car , which stumped the RAC man and prompted my first carb rebuild. Float valve was sticky , you can't get uphill on an empty stomach!

Pertronix ignition is in the future when funds permit (I have several old cars to spread the love around). I will also R&R the distributors one day. For now , I'm pretty happy with the way the cars run, but will keep tinkering, testing and learning as I go. Thanks for your comments!

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