M42 ignition problem

[Mark508f]

Hi, I'm having some problems with my M42, most of the time it runs fine but if I'm just cruising along between 2000-2500 revs the engine stutters as if not all the cylinders are firing, if I take off the ht leads and clean the connections on the leads and coils the problem goes away, but it always comes back in a couple of weeks, the plugs are new and I have tested the resistance on the coils which seem fine (although they are second hand so I can't be 100% sure) so I am assuming it's the leads but I'm struggling to find anywhere that sells new leads for an M42, has anyone experienced a similar problem? Can anyone point me in the direction of somewhere that sells leads? Also I was wondering about doing the coil on plug conversion, is that something worth doing, any advice would be much appreciated.
Thanks
Mark

[arrisbmw]

have you cleaned the distributor and rotor . worth a go . clean the copper parts in both till you can see nice shiny metal. i use a small file on the rotor arm and a small sharp scew driver inside the distributor cap, no need to clean the carbon tip in centre just make sure it springs in and out.

another idea run the engine at night no lights , have a touch handy then turn it off. look at the leads in the dark. you should NOT be able to see any sparks

if you can there ,s your problem something is shorting out to earth.

[Mark508f]

Thanks, the M42 doesn't have a distributor, it has a coil for each plug, but yes hadn't thought about checking the leads that way, will give it a go later on.

[Mark508f]

I ran the engine in the dark last night and no sign of any sparks, still feel like it must be the leads though as the problem goes away when I clean the connections, another possibility is, I don't have the plastic cover that goes over the coils so was wondering if maybe water is getting in there and causing a bad connection? As I don't seem to be able to find a new set of leads anywhere online I'm guessing they're going to have to come from the main dealer, wondering if maybe the coil over plug conversion might be the cheaper option?

[arrisbmw]

you can check the leads with a multi-meter on ohm. google it. resistant should all be about the same. can,t rember what should be.