Does anyone know what this part is called?

Wobdog

Wobdog

a.k.a Mike
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Sorry for my ignorance but I do not know what this is called. Need part name and were to purchase
 

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If you remove it, it should say the ohm reading somewhere. Ebay. Are you running points or electronic ignition?
 
its #22 on the wiring diagram its the Primary Resistor. the green wire is fed by fuse 6 and the black / red wire goes to the coil.
 
This resistor reduces the voltage drop on the coil during normal running condition, thus avoiding overheating of the coil.
Only during starting this resistor is bypassed allowing full voltage drop on the coil.
On the first models this was installed as an external resistor as shown above. After '74 models had this resistor implemented in the cable running to the coil.
So verify first if you really need this resistor as a dedicated part.
There are two different cable drawings, one for pre-face-lift and one for models from '74 onwards.
If you want to install electronic ignition you might not need this resistor any more, but this is another story.
I might have some available, new and probably used ones.
17410773896064024067833418761694.jpg20250304_093924.jpg20250304_093914.jpgThomas
 
available, NOS, 150 euro asking price:
www.kleinanzeigen.de

BMW E3,E9,E10,21... Vorwiederstand Zündspule NOS

Zustand Neu,BMW E3,E9,E10,21... Vorwiederstand Zündspule NOS in Nordrhein-Westfalen - Overath
www.kleinanzeigen.de www.kleinanzeigen.de
1741080407630.png


Does it matter that this one is 2 cilinders and looks to have 4 connectors? Can you choose how to connect it, as it read 0,4 and 0,6 Ohm on it?
The one on my car is a single rectangular block with just 2 connectors; like in the schematic drawing in post# 5 above.
 
....should be written on the coil's label:20250304_103526.jpg
You may connect on the left side and on one connector on the right side, then you should get the respective ballast as written. Or you connect both in line on the right side then you get the sum of both values20250304_110243.jpgThe resistors shown above are something special and quite expensive, standard ones are available at reasonable prices.
Note: the ballast resistors might get hot during operation, so always install them properly using the metal holder which works as a heat sink.
Thomas
 
Last edited:
TomHom said:
....should be written on the coil's label:View attachment 198724
You may connect on the left side and on one connector on the right side, then you should get the respective ballast as written. Or you connect both in line on the right side then you get the sum of both valuesView attachment 198731The resistors shown above are something special and quite expensive, standard ones are available at reasonable prices.
Note: the ballast resistors might get hot during operation, so always install them properly using the metal holder which works as a heat sink.
Thomas
Click to expand...

this double barrel resistor is used in TDZ ignition, i use one of those for my bosch setup, it came with the TDZ ignition kit together with an special blue coil
 
Check with your local parts store, these are not used just by BMW All you need is the correct OHM reading

The ones that the other fellows are showing are special ones used with hi voltage electronic ign systems

Thanks, Rick
 
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