A couple of weeks ago I organised a mobile Crypton tuning firm to sharpen up the running of my series 2. The guy travelled a long way and arrived on time. He spent around 1.5 hrs adjusting the carbs and claimed to have adjusted the timing. I clearly recall hammering during the course of works. I took the car for a short local drive when he finished and whilst it ran well at lower revs it had a misfire above 2500 rpm which it didn't have before. He said the carb needles might be worn and advised replacement. I took his word for it at the time but subsequently decided to check the timing myself in case his adjustment had caused the misfire. The distributor was stuck solid and it soon became apparent what all the hammering was about. There's no way he could have made any adjustment at all.
His efforts had damaged the unit and the drive shaft had sufficient sideways movement to open and close the points without rotation which was clearly causing the misfire. I don't believe he should have taken this approach, at least without discussing the issue with me. None the less damage was done so my only option was to pursue freeing up the distributor. This made matters worse and the engine misfired regardless of rpm. At this point it was clear the distributor would need replacement or a full re-build and had to come out.
I eventually resorted to using a long pry bar with moderate force but it still wouldn't move at all. Obviously I was concerned about breaking the unit and leaving the siezed distributor base stuck in the enging block. As we know, the distributor isn't very accessible and after much thought I concluded the only option with minimal damage was to somehow pull it out. I didn't really want to use heat around that area so had a look at what tools I had.
What I did was cobble together a cordless impact wrench (such as you'd use for wheel nuts etc.) a 13mm hex impact socket and a set of wide 13mm hex chisels. The idea is not to chisel away at anything but use adjacent parts of the block to stop the chisel spinning and rely on the rapid vibration just as you would with loosening a wheel nut. Using a variety of chisels I first managed to get the unit turning sideways and then set to work with a thin wide chisel underneath the distributor. This worked really well and I have no idea how I would have removed the distributor otherwise. The steel / alloy corrosion had occured between the o-ring and base of the unit where there is no oil. In this case the distributor was ruined because it was unbelievably stuck, however it came out in one piece which is excactly what I wanted. I think in a less serious scenario the same would work without damage if protective material was used between surfaces. I'm now taking this opportunity to fit a 123 Tune + distributor and hope it goes well ! I'm not the first and won't be the last person with a stuck distributor and hope this might help anyone in a similar position.

 

Great write-up. Some day this is going to be invaluable to someone with the same problem. And thanks for providing a nice descriptive title so it will be easy to find.