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dade
United Kingdom
513 Posts |
 Posted - 12/07/2021 : 11:12:22
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I recently had an Ignition problem with my MG TD, after checking through the ignition system I deduced the failure of the Coil.
The failed coil was modern replacement with a silver foil "Lucas" badge, I reckon that it had been fitted about 5 years ago, the coil that I removed then was the original fitted in 1952!
My question is can any one suggest a good replacement as I do not want to replace a coil with the same version.
Russ
PB0333 |
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Simon Johnston
United Kingdom
6163 Posts |
Posted - 12/07/2021 : 12:40:24
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Russ,
I find the Bosch Blue coil - part number 0 221 119 027 - very satisfactory. It’s a current model (for the VW Beetle!), not some repro rubbish, and has screw terminals for the low tension connections. The high tension is a push in connection. If you peel off the Bosch label and give it a coat of black paint, no one will know! I bought mine from my local GSF Car Parts store.
Simon J
J3437 |
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Reinout
USA
223 Posts |
Posted - 12/07/2021 : 15:14:01
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Emma had many, sometimes intermittent, failures with all kind of coils: old Lucas, new Lucas, high performance Lucas, remanufactured pre-war Lucas look-alikes ... etc. Noise and/or voltage spikes from the three-brush generator may have been a contributing factor, I am not sure. But since installation of a blue Bosch (painted black as suggested by Simon), two years ago, I have seen no more failure. There are several different blue Bosh coils models. Googling around a bit amongst VW Beetle sites suggest that the Made in Brazil, metal case, resin filled model is the one to use.
Reinout Vogt
Emma
1931 M-Type 2M/2735 |
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Simon Johnston
United Kingdom
6163 Posts |
Posted - 12/07/2021 : 16:02:00
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The part number I have quoted above is the made in Brazil version and painted black it looks just fine!
Simon J
J3437 |
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Gordon
United Kingdom
693 Posts |
Posted - 12/07/2021 : 17:45:38
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Simon,
Do you know the resistance values for the coil?
Gordon
ex owner of PB 0331, MG4473
Derby |
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BobH
United Kingdom
261 Posts |
Posted - 12/07/2021 : 21:17:59
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Gordon, that coil is quoted as:
12V high output coil, Primary 3.4 Ohms, Secondary 7.8k Ohms |
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Simon Johnston
United Kingdom
6163 Posts |
Posted - 12/07/2021 : 21:42:49
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Gordon,
I asked Bosch the same question some years ago and they said:
Resistance:
Primary: 2.55 #8486; - 3.15 #8486;
Secondary: 6.2 k#8486; - 9.8 k#8486;
Inductance
Primary: 7.20 mH - 10.8 mH
Secondary: 32.8 H - 49.2 H
I’m afraid I do not have a precise output voltage figure that Mr. Johnston is requesting. The old technical customer information document is 40+ years old and does not have much data unfortunately.
The term ‘high energy’ is a more generic reference to the overall HV output of such an ignition coil type, given that 12V is converted to an output of thousands of volts of high voltage, thus producing ‘high energy’ required for spark ignition.
I have included a screen shot below of an old catalogue from 2005 to give some reference to the actual (secondary) high voltage outputs of the Bosch ‘traditional’ type coil range. The 0 221 119 027 is the blue coil in the image below.
It’s also quite difficult to be exact when discussing figures for high voltage output (e.g. 40kV), as often a coil might be used in conjunction with an external ignition amplifier unit, depending on the specification for the whole ignition system. Generally these older types of traditional ignition coils (cylindrical housing with asphalt or oil filling) will not produce much more than 25 kV stand alone, due to the nature of the winding specification and insulation materials.
Simon J
J3437 |
Edited by - Simon Johnston on 12/07/2021 21:53:29 |
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Gordon
United Kingdom
693 Posts |
Posted - 13/07/2021 : 11:37:02
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Simon,
Thanks for that information. Clearly the actual voltage developed in use will depend on many factors including plug gaps, compression ratio, fuel mixture, amount of oil and state of plugs etc!
Gordon
ex owner of PB 0331, MG4473
Derby |
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Simon Johnston
United Kingdom
6163 Posts |
Posted - 13/07/2021 : 12:47:35
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Exactly, Gordon, which is why fitting a fancy 'sports' coil will not on its own result in a higher voltage spark.
Simon J
J3437 |
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dade
United Kingdom
513 Posts |
Posted - 13/07/2021 : 15:40:05
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Hi Simon
Thanks again for your prompt reply, I now have plenty of info regarding coils, its a component that just sits there and gets forgotten, however when it fails all sorts of problems ensue.
Thanks again
Russ |
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Simon Johnston
United Kingdom
6163 Posts |
Posted - 13/07/2021 : 16:44:55
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quote:
Originally posted by dade
…however when it fails all sorts of problems ensue.
Been there, done that 
Simon J
J3437 |
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