Update. With my newly acquired tacho cable - thanks to the good work by the guys at Flexible Drive Agencies, who used some of my old fittings to rebuild
me a new cable - I can now see I am pottering around at 1500 rpm
with a temp of 65 deg C, doing 6.4 knots. If I up the rpm to 2000 the temperature comes up to a much more likable 80 deg C and settles there. We are now doing just under 8 knots.
So looking at the temperature change, I am guessing I dont even have a thermostat installed as my web research
seems to indicate the correct one opens at 78 deg C. I also wonder if the extended running at the lower rpm and cooler temperature could have glazed the bores or it she still working hard enough even at that low load not to glaze up? I did note at 2000 rpm she was putting out a fair bit of black exhaust
....not at all what I would call excessive, just what you would expect at the higher work load.
I believe maximum rated continuous rpm for my engine is 2400. Is that correct? Should the exhaust look darker at that sort of load or am I pushing her too hard? It might well be time for an injector service
Thanks for you input,