Club 80-90 Forums

after running problems i have replaced my OLD bosch coil,black body, with a blue beru zs 106 as supplied by local garage, the van is electronic ignition and have now seen the same coil on websites saying for use ONLY with points ignition, the van runs great with it though......but will it damage it ??..........any advice ?

I cannot answer your question with a simple yes or no, but, if you take the wires off the 2 small terminals, then get your meter out and measure the resistance figure and let us know what it is, "we" can compare that to the spec for the standard coil, using the table on this Brickwerks page. If it is in the same ball park it won't do any damage.

That's the African coil for T3 with point ignition, also same as Bosch Blue coil etc.

If it was my own I would just put and early [transistorised ignition] coil on it.

Any difference in primary resistance may shorten the life of the ignition amplifier.

will test the coil tonight and if wrong i can rectify with a resistor in line i guess rather than another new coil ??

banjax34 wrote:will test the coil tonight and if wrong i can rectify with a resistor in line i guess rather than another new coil ??

Sorry but I don't think that will work as it will lower the voltage reaching the coil. Simon really knows his stuff, so I would take his advice

banjax34 wrote:after running problems i have replaced my OLD bosch coil,black body, with a blue beru zs 106 as supplied by local garage, the van is electronic ignition and have now seen the same coil on websites saying for use ONLY with points ignition, the van runs great with it though......but will it damage it ??..........any advice ?

if the garage supplied it wrong and funds are tight ask the garage to replace it with the correct coil, and offer to pay the differnce

measured it (disconnected) and it is well out of range in the brickwerks chart for an early coil and even the later ones,(mine should take the early din plug coil) the primary resistance is 3.5 ohms and secondary resistance is 7.8k ohms, the brickwerks site says .52-.76 ohms primary and 2.4k - 3.5k ohms secondary,so can anyone explain what damage a higher resistance coil can do to early (1982 2.0l petrol) electronic ignition systems ? i should add that the original coil failed on our camping trip to cromer and fitted the beru coil which i had as a spare on the van, the drive back to london non stop was a revelation in terms of performance, the van actually pullled going uphill, fully loaded with camping gear.wife two kids and four bikes ( 3 on rack) !!! normally it slows and you think uh oh until you realise its a hill and then change down etc etc, but with this coil it went like stink, i'm sure a new correct coil will be the same, but as i said would a higher resistance coil cause problems ? thanks for all replies so far, cheers

another question which may help, if you upgrade from points to electronic ignition do you have to change the coil? if not then my points coil would be ok, does a higher resistance coil produce a weaker spark ??

Re a higher resistance primary. Well the simple view is it won't damage the ignition amp. But, it's not as simple as just resistance. The reason is, it is a coil of many thousands of turns so it also has a thing called "inductance" and that will be a very different value too. Also there is "back emf" which is a voltage developed as the magnetic field collapses, (which it does at every spark), this send a voltage back down the wire to the ignition amp and on your new coil, this voltage may be higher than the ignition amp is designed for. Then there is the breakdown voltage of the output device (transistor) in the ignition amp, this will be affected by the higher values.

But it might be fine for years

banjax34 wrote:another question which may help, if you upgrade from points to electronic ignition do you have to change the coil?

I would say yes, but that is just my take on it. Others may be along to confirm (or otherwise).

banjax34 wrote:if not then my points coil would be ok, does a higher resistance coil produce a weaker spark ??

No, it's the opposite. An ignition coil is just a "step up" transformer. The ratio of turns on the low voltage side, compared to amount of turns on the high voltage side, determines the output voltage and current (and therefore the strength of the spark). At 12 volts in, if (hypothetically) you had 1000 turns on the primary and 1 turn on the secondary then you would get 12,000 volts out (12 x 1000). Of course in the real world there are a heck of a lot more turns in an ignition coil than that example

If it were I, I think I would change it for a proper one and either get your money back off the place that sold it you, or flog it on to a classic car nut who has points in there vehicle. Or, keep a spare ignition amp on board as a "get you home", just in case