123 DISTRIBUTOR WIRING - Q? Ballast resistor?

[Bshaunessy]

Wiring advice pls:1970 stock 280 SL.  I’m replacing stock Bosch distributor with 123 ELECTRONIC DISTRIBUTOR ( specific to 280 SL New Electronic Ignition Distributor

Fits Mercedes W113

Vintage Euro Parts SKU: VEP102535)

     Supplied wiring diagram recreated below shows two wires from new distributor : black direct to negative side of coil ( re-using stock Bosch coil) and red direct to +15 side of coil.
    The suggested wiring effectively  RETAINS  the stock 0.6 ohm ballast resistor.  TECH MANUAL indicates ballast resistor is bypassed during start ( full 12v with to coil) and is in ignition circuit during run…….ballast resistors  job is to cut amperage draw to coil to half of the amperage draw during start sequence ( to reduce arcing on points……..but new electronic ignition has no points!??).
     A recent Jon Bernardí ; Tyler S article in Sept 2022 PAGODA WORLD ( great article BTW…..inspired me to bu a new 123 distributor) specific to installing 123 DISTRIBUTOR recommends wiring ,per 123, direct to coil BUT JUMPERING OUT BALLAST RESISTOR? ( unclear why this step was taken)

So the question is: eliminate ballast resistor per PAGODA WORLD recommend ( coil sees full 12v in run condition) OR include ballast resistor per  123 recommend ( coil sees lower than 12 v  during run)?

[merrill]

hi
i plan to install the 123 on my 66 as well

as suggested somewhere  bypass the ballast but do not remove it from the car.  keep the old distro in the car and if the 123 fails
its not too much work to hook everything back up to use the old distributor.

[dirkbalter]

No ballast resistor as per 123.
You should have a little booklet with a wiring diagram included with the distributor?

[Bshaunessy]

Dirkbalter: thx for reply.
  Yes, I received the install booklet with the 123 Distributor as you have shown.   Correct that this generic drawing does not show ballast resistor…..but drawing is not specific to w113 ( which has a ballast resistor in ignition circuit).
   I have read several posts that indicate the intent of the ballast resistor is two fold: (1) reduced amperage through conventional points ( no longer applicable with 123 electronic ignition) AND (2) Reduced amperage through stock coil…..reducing premature wear from overheating ( still applicable with 123 electronic ignition.)

   I shall wire up WITHOUT ballast resistor ( will leave in place and jumper out)  and see how it goes.

[dirkbalter]

Dirkbalter: thx for reply.
  Yes, I received the install booklet with the 123 Distributor as you have shown.   Correct that this generic drawing does not show ballast resistor…..but drawing is not specific to w113 ( which has a ballast resistor in ignition circuit).
   I have read several posts that indicate the intent of the ballast resistor is two fold: (1) reduced amperage through conventional points ( no longer applicable with 123 electronic ignition) AND (2) Reduced amperage through stock coil…..reducing premature wear from overheating ( still applicable with 123 electronic ignition.)

   I shall wire up WITHOUT ballast resistor ( will leave in place and jumper out)  and see how it goes.

Well, I was told to eliminate the resistor. I am running the 123 without resistor, but with a new black Bosch coil, for a number of years now on a 280 (108), and have no issues.

[Benz Dr.]

Black coil is 13KV and the red one is 26KV. I'm not sure what the blue coil runs but suspect it's somewhere in between at 20KV. Ballast resistors protect the coil and the points, and in particular, when the points are closed with the ignition on.

You should be able to run electronic ignition with whatever coil you want. Modern MB ignition systems still use solid core wires so I think you would be safe using those. 

[dirkbalter]

@benzdoctor, are you sure about the voltage of the black coil?
I seem to remember 25 KV.

[Benz Dr.]

A guy from Bosch told me that years ago so I went with that. The red coil is stronger so I tended to believe it.

[Bshaunessy]

123 DISTRIBUTOR INSTALL UPDATE….SUCCESS!
   Successfully installed , and timed (8 degrees ATDC idle, 35 ish degrees ATDC@3000 rpm).  Car runs well ( although here in 🇨🇦, it’s getting rather cool for top down test drives).   Installed new PERTRONIX FLAMETHROWER 3 ohm coil as well.
  Eventually wired as per below

[FresnoBob]

Did you purchase the bluetooth version?  I've been experimenting with various timing curves and now prefer 39º at 3,000 rpm and only 6º at 500 rpm.  The car starts and runs better than ever.  I also deleted the ballast resistor once I installed the 123. 

[Bshaunessy]

FRESNO BOB
  No, I did not upgrade to Bluetooth model.  I have enough trouble with the myriad of other Bluetooth devices in my life and didn’t want to complicate my simple 280 life.
  However, if it works, I can certainly see the merit of being able to fine tune your timing from the drivers seat vs under the hood., trial and error.

[thelews]

It works, and very well.

[Tyler S]

Hey All, Thought I would add some info regarding the ballast resistor and the 123 Ignition. If your primary coil resistance is lower than 1 ohm then you need to either replace the ignition coil OR keep the ballast resistor in circuit WITHOUT a jumper wire.
If you choose to keep the ballast resistor and low impedance coil then I advise you to hook the 123 red power wire to the keyed 12+ ignition side of the ballast resistor instead of coil +
If in doubt just replace the coil with one recommended by 123 Ignition and bypass the resistor with a jumper wire.
Hope that clears up some confusion.

[teahead]

Ya, pretty sure I installed a Bosch blue coil and jumped the ballast resistor so it looks sorta stock.

[Benz Dr.]

123 DISTRIBUTOR INSTALL UPDATE….SUCCESS!
   Successfully installed , and timed (8 degrees ATDC idle, 35 ish degrees ATDC@3000 rpm).  Car runs well ( although here in 🇨🇦, it’s getting rather cool for top down test drives).   Installed new PERTRONIX FLAMETHROWER 3 ohm coil as well.
  Eventually wired as per below

Don't you mean 8 degrees BTDC at idle? Ignition should run 38 - 39 degrees full advance which is at or before 3,000 RPM.

[Pinder]

Hi Everyone

I am contemplating installing the 123 ignition in my 1970. Should all the emissions stuff be by passed?   currently my car is running OK. I  think a bit sluggish on flooring it at higher speeds and maybe idle could be smoother.

I currently have the Comp Cams electronic ignition installed from back in 2015 / 16 .

 Best Regards

 Pinder

[Bshaunessy]

Dr Benz:
  Yes, sorry.   8 degrees BTDC ( not ATDC).