Distributor Cap HT lead positions
Posted: Mon Mar 14, 2016 12:02 am
I've been (unsuccessfully) trying to track down a slight misfire recently; thus it was with a dull sense of inevitability that I realised that I'd have to take the distributor cap off. It has been undisturbed for several thousand miles / about two years or so (following the infamous disintegration of my rotor arm), so overdue an inspection anyway.
On a fairly balmy spring morning, with tools to hand and in no special hurry, it is a vastly more pleasant job than by the side of the road in a chilly breeze. It is so much easier once the fan (and fan shroud) is off, I have decided to pack a 32mm wrench in the car tool kit, so that if I ever need to remove the distributor cap again, I'll be able to do it easily. The other trick is to remove the radiator top mounts (not all E24 versions) and this allows another few mm clearance because the radiator can swing forwards a little.
I found that the distributor cap was actually pretty good, just a bit dusty inside really. The rotor arm still looks like new more or less too. Both parts are pattern parts, not OEM ones. The cap was the same one as survived the exploding rotor arm, and is at least 15 years old.
I cleaned it up the distributor cap inside and to make a proper job of it, I thought I ought to clean the outside too. Once I got the leads off, I realised that, unlike an OEM Bosch part, this pattern part
didn't have the correct locations for the plug leads marked on it anywhere. D'oh! I remembered making a mental note, a long time ago, to mark the correct lead locations onto the inside of the black distributor cap cover, but then didn't do it because I didn't have my vibro-etch to hand, and wanted to make a neat job of it. This time I just had at it with a screwdriver.
For the reference of others, the six pins inside the cap at 1 o'clock, 3 o'clock, 5 o'clock, 7 o'clock, 9 o'clock, 11 o'clock are cylinder #s 3, 5, 1, 4, 2, 6.
Similarly the connections left to right in the photo are 2,4,6,ZS,3,1,5 where ZS is the coil (king lead) connection.
I also cleaned my spare distributor cap; this OEM Bosch one was very manky indeed, but with application of much elbow grease and not a little solvol autosol polish, it came good too. I used cotton buds (Q-tips) to clean the inaccessible nooks and crannies. No single solvent would ever shift every kind of crud from the inside of a distributor cap, but the solvol autosol cleaned everything nicely. Small scuffs and scratches can be polished out using solvol too.
BTW the carbon brush ought to protrude about 5mm from the centre pillar. If the brush is a little worn, often the spring underneath can be reset slightly to allow the correct brush protrusion.
cheers
On a fairly balmy spring morning, with tools to hand and in no special hurry, it is a vastly more pleasant job than by the side of the road in a chilly breeze. It is so much easier once the fan (and fan shroud) is off, I have decided to pack a 32mm wrench in the car tool kit, so that if I ever need to remove the distributor cap again, I'll be able to do it easily. The other trick is to remove the radiator top mounts (not all E24 versions) and this allows another few mm clearance because the radiator can swing forwards a little.
I found that the distributor cap was actually pretty good, just a bit dusty inside really. The rotor arm still looks like new more or less too. Both parts are pattern parts, not OEM ones. The cap was the same one as survived the exploding rotor arm, and is at least 15 years old.
I cleaned it up the distributor cap inside and to make a proper job of it, I thought I ought to clean the outside too. Once I got the leads off, I realised that, unlike an OEM Bosch part, this pattern part
didn't have the correct locations for the plug leads marked on it anywhere. D'oh! I remembered making a mental note, a long time ago, to mark the correct lead locations onto the inside of the black distributor cap cover, but then didn't do it because I didn't have my vibro-etch to hand, and wanted to make a neat job of it. This time I just had at it with a screwdriver.
For the reference of others, the six pins inside the cap at 1 o'clock, 3 o'clock, 5 o'clock, 7 o'clock, 9 o'clock, 11 o'clock are cylinder #s 3, 5, 1, 4, 2, 6.
Similarly the connections left to right in the photo are 2,4,6,ZS,3,1,5 where ZS is the coil (king lead) connection.
I also cleaned my spare distributor cap; this OEM Bosch one was very manky indeed, but with application of much elbow grease and not a little solvol autosol polish, it came good too. I used cotton buds (Q-tips) to clean the inaccessible nooks and crannies. No single solvent would ever shift every kind of crud from the inside of a distributor cap, but the solvol autosol cleaned everything nicely. Small scuffs and scratches can be polished out using solvol too.
BTW the carbon brush ought to protrude about 5mm from the centre pillar. If the brush is a little worn, often the spring underneath can be reset slightly to allow the correct brush protrusion.
cheers