i am the second owner of a 1972 250c. i believe the car to be in original state (original carbs). i am confused about the values for the air correction jets. mine are 110 primary 130 secondary. a 250c in the bone yard is 130 primary 110 secondary. The website http://jaimekop.com/CarbManual/index.html states that my car should be 180 primary 110 secondary. this website document seems counter intuitive for the 72 because all the other setups have smaller values in the primary. my secondary emulsion tube is 4N, the primary is not marked i assume it to be K30584. is it that the K30584 emulsion tube in the primary needs a larger air correction of 130 or 180? is the 180 value from the web document a typo? if i run the rig with the two tubes backwards will one side (primary/secondary) be rich and the other lean? are my 110 and 130 air correction tubes close enough that i will not notice a difference?

I rebuilt the carbs and put 110 in the primary. valves adjusted, carbs tuned .engine timed. then re adjusted. car runs well enough but should i go with 130 in the primary. I will be putting a pertronix setup in this week and want to get the rig as clost to perfect as possible. any advice about the air correction tubes would be greatly appreciated. if you have a 1972 250c i need to hear from you. please help.

There are several mercedes models with zenith carbs. Each is slightly different. It gets complicated in the 70's. Note that the following data is from the 1972 TDM's (Technical Data Manuals), which are still available from mercedes at 1-800-for-merc (presuming this site doesn't sell them).


Type: M130, 1972 US emissions
Carb: 2 x Zenith 32/40 INAT
Barrell: 1st 2nd
Venturi "K": 20 28
Main Nozzle "Gg": x100 x130
Air correction "a": 180 110
Emulsion tube "s": mm 1.7 4N
Idle fuel nozzel "g": 45 -
Progressive fuel jet: - 70
Idle air bore: 1.4 -
Progressive air bore: - 1
Injection quantity: 0.7 - 1.0
Injection tube: 0.5 -
Start of injection: immed.
Float needle valve: 2
Float weight g: 8.5
Float ajustment mm: 21 - 23 (note 7)
Float chamber air-bleed: not adjustable
Choke gap: 2.0 - 2.2
Automatic starting device: to mark
bypass air bore: 0.8 / .08 / 0.8 / 0.9
starter cover designation: both 24

(you'll have to guess a bit on the columns, tabs are not preserved here)
-CTH

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