Have just obtained a very beaten up series III that has been on a farm for
20 years or so. Petrol 4 cylinder circa 1972. Was running on 3 cylinders and after redoing head was back to 4 cylinders (valve seats really poor but OK'ish now). Runs fine but dies if you back off the throttle too quickly at low revs (like less than 2000rpm). If you ease off very carefully it will hold and idle smoothly - well most of the time. Have played around with the carby jet settings (over full range) but makes no difference. Used to idle better when only running on 3 cylinders and bugger all compression due to leaky valves. Any ideas gratefully accepted.