"I read that there should be a resistor somewhere but I can't find it in the engine bay."
Rather than having something which looks like a resistor, it's far more common to have a "ballast wire", which looks just like any other wire, except for being a bit chunkier. It has a higher resistance than normal automotive wire. The total length of the wire (it runs from the ignition switch to the coil) will be just the right length to provide about 1.5 ohms resistance.
If you have any doubts that the PINK/WHITE wire really is a ballast wire, turn the ignition off, and place a multimeter between the positive terminal of the coil and the terminal on the fuse box which has the white 'ignition' wire on it. The reading should be 1.5 ohms or thereabouts. If it were standard automotive wire, the resistance would be negligible (a fraction of an ohm).
(The following is from Wiring diagram 18 in Haynes manual, which applies to 1988-on carburettor models. I believe this applies to any Mini with a factory standard ballast set-up, but check with the appropriate wiring diagram first).
The easiest way to tell if you have a "ballast wire" set up is to check that there are TWO wires connected to the positive terminal of the coil (on some coils, e.g. Ducellier, the positive terminal is labelled '15'). One will be PINK/WHITE - this is the ballast wire which acts as a 1.5 ohm resistor, and runs directly from the ignition switch. On my Mini, it also had "resistive" printed on the wire every couple of inches. The other will be WHITE/YELLOW - this is the standard non-resistive wire which runs from the solenoid - it only operates when the starter motor operates.
Regardless of whether you have a 'ballast' or 'non-ballast' set-up, there will be a WHITE/BLACK wire connected to the negative terminal of the coil (on Ducellier coils, the negative terminal is labelled '1').
Because these ballast wires have a bad reputation, some replacement ballast coils come with their own ceramic resistor which can optionally replace the ballast wire (you would bypass the whole ballast wire by connecting a new length of automotive wire - of the correct AWG rating - between the positive terminal of the coil and the ignition spade on the fusebox - the ceramic resistor would be placed somewhere along the length of this new wire). For example, I know some or all Lumenition ballast coils come with their own ceramic resistor.
All 1986 998cc Minis came factory-fitted with a ballast wire and ballast coil, but bear in mind that many will have been converted over the years to have a non-ballast coil (the ballast wire will have either been bypassed or removed entirely).
As Cooperman says, it's probably safer to fit a standard 3 ohm 12V non-ballast coil. It's very simple - you just have to disregard the WHITE/YELLOW and PINK/WHITE wires which are probably currently connected to your ballast coil (tape them up safely out of the way). You then have to run a new wire (check for the appropriate current rating) directly from the positive terminal of the coil to the ignition switch (fusebox is the most convenient place - the terminal that the white ignition wire goes to - there should be a spare terminal immediately above it). Nothing changes about the WHITE/BLACK wire, just connect it to the negative terminal as before.
If you really want to keep using a ballast coil, buy one which comes with a free ceramic resistor and use that instead of the factory-standard ballast wire.
Edited by zero_wlv, 09 September 2016 - 09:08 PM.
