W113 Pagoda SL Group > General Discussion

COILS and BALLASTS

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JimVillers:
Michael .... Have you put an ohm meter on the coils to measure the internal resistance.  I would be surprised if each of the blue coils had a different resistance.

Jim Villers
190SL, 230SL 5-Speed, 190E 2.3-16 Kompressor, MGB 5-Speed

mdsalemi:
quote:Originally posted by JimVillers

Michael .... Have you put an ohm meter on the coils to measure the internal resistance.  I would be surprised if each of the blue coils had a different resistance.

Jim Villers
190SL, 230SL 5-Speed, 190E 2.3-16 Kompressor, MGB 5-Speed

...why yes I have.  My trusty Fluke 77 meter, to be exact.

I have a Bosch Blue, made in Germany, that reads less then 1 ohm, near zero.  I have a a Bosch Blue made in Brazil, reads 3 ohms.  I have a Bosch Blue made in Mexico that also reads 3 ohms.  The Mexican coil says "without resistance".  The German coil says "Transistorized".  I also have a Bosch Red coil, made in Brazil, that reads near zero, and this says requires 1.8 ohm external ballast, but also says on the box for "older, non transistorized ignitions".  Aside from the small label that reads "transistorized" (and the different primary resistance) the Blue Brazil and Blue German coils look alike; the Mexican looks very different.

Can you see the confusion here?  No two alike.

Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored

DavidBrough:
Hi Michael,

If it helps, I also have a 1969 280SL and recently changed the standard blue coil for the high power red one, the corresponding ballast resistors are also colour coded so if you have a new red coil you will need the red ballast resistor to go with it (1.8ohm). I understand that this gives a better spark than the standard blue parts and I have had no problems with it. As long as your ignition is standard for the year i.e. the early non transistorised variety, I would remove the current incorrect coil and fit the red label parts. There is much comment on the site regarding the technical aspects of various set ups including chaning to transistors but this can be confusing. I just stuck with the straight forward main dealer matched label colour parts and it works well.

mdsalemi:
quote:Originally posted by DavidBrough

Hi Michael,

If it helps, I also have a 1969 280SL and recently changed the standard blue coil for the high power red one, the corresponding ballast resistors are also colour coded so if you have a new red coil you will need the red ballast resistor to go with it (1.8ohm). I understand that this gives a better spark than the standard blue parts and I have had no problems with it. As long as your ignition is standard for the year i.e. the early non transistorised variety, I would remove the current incorrect coil and fit the red label parts. There is much comment on the site regarding the technical aspects of various set ups including chaning to transistors but this can be confusing. I just stuck with the straight forward main dealer matched label colour parts and it works well.



Hello David,

I do indeed have the red coil and 1.8 currently in the car.  That does not change my curiosity as to why there are so many different blue coils!

Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored

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