Congratulations Malcolm! I doesnt seem that long ago when you couldnt get the car to run and now you are achieving marathon mileages!
You never did tell us what the problem was??
Thanks Bob. That was when the piston rings had stuck into their grooves at the front of the piston. It looked like everything was fine until I took the barrel off. The engine still had some compression, but not very much. Anyway I managed to ease the rings out without breaking them and cleaned up the grooves and it worked after that.
The run up to Nottingham was really good. I even got up to 54 mph on the sat nav on one flat stretch although it was more usually 40 - 50 depending on undulations. Conversely, at one point I had to stop for a car turning right at the bottom of a big hill on the A429 at Fossebridge and was crawling along at 7mph in 1st by the time that I reached the top, fortunately on that stretch of road there is a crawler lane.
What I'd finally realised after yet more running was that although the fuel tank holds about 2 1/2 gallons when it's full, when it was getting down to about a gallon or so, the fuel pressure from the gravity feed wasn't sufficient to keep up with demand and you'd get fuel starvation even though it looks like you've still got plenty left in the tank. Also, my car can't cope with mixing the petrol/oil in the tank. Mixing it in a can beforehand and keeping the tank brimming on the trip worked like a dream. My only other mistake was missing a turning in some roadworks and ending up on the M69 for a bit. Fortunately no problems, but not something I'd be keen to repeat.
Of course I still hadn't properly sorted the issue that had stopped the car on the way up to Wales the other week, when the thread in the carb where the banjo bolt screws in had partially stripped. I'd adopted Dave Millers suggestion and used non-setting gasket goo as a temporary fix, but the banjo bolt eventually started vibrating loose and consequently fuel starvation became a problem on the way back, I stopped and redid the temporary gasket in Tesco's car park at Ashby-de-la-Zouch on the way back, and things looked OK for a while, but by the time I got to Stretton-on-Dunsmore, I was stopping every few minutes and what had been left of the thread had given out entirely - even with some cable ties to clamp the bolt to the carb, it was leaking like a sieve. I took out the outer fibre washer and used gasket goo on that joint as well, but though that did allow the bolt to tighten and gave a much better joint than previously, some of the goo was obviously interfering with the filter and restricting the fuel flow so that even with the tank full, I couldn't pull full revs going up hill. I knew I was getting into the hilly bit of the Cotswolds and I was also getting a bit conscious of stalling on a big hill with a load of traffic behind me so I abandoned the attempt a little bit further on. Still I'd managed 154 miles to Nottingham and just under 100 miles on the way back, so a massive improvement on any run I'd managed previously. Very pleased to have come 2nd in the concours having driven to the event. Now I'd better get on and sort the carb out properly!
I've also got to look again at the fuel pipe run. there's very little drop between the tank and the carb on the Bond, but quite a long fuel pipe to cope with the 180 degrees you can turn the engine. I'd copied the pipe run from some under bonnet photos from the 1950s, but I suspect the original fuel pipe was a bit stiffer than the one I'm using, and that little bit of extra droop in the pipe is sufficient to cause problems when the tank isn't quite full.