the 3/4 tube that goes into the block at the back is actually the positive crankcase ventilation tube, it connects to the intake manifold just under the carburettor and is designed to just keep the block fume free. To prevent the head gasket blowing again try using a larger radiator like a dihatsu or gemini one, they hold more coolant and if used with a good sized thermo fan they will have no problem keeping your engine cool on the hottest of days

Hello All.
Is there any one out there that has a coolant flow chart that is readable?
I have a 1971 1200 that I am using for a power source for my generator. I recently blew the head gasket on it and upon removing and cleaning the mess up I noticed that the 3/4" steel tube that protrudes from the rearmost part of the block just under the exhust manifold has no noticeable opening into the main cooling jacket suronding the cylinders. So I am puzzeled as to were it gets it's coolant source from and why! Can any one give me some ideas or some facts supported by a coolant flow chart..
The reason I am using this for a power source for my generator is that I live 3 miles from the closest power pole. I have 20 8D batteries that feed my inverter to give me A/C current for normal household use. Those 8D batteries need to be charged regularly and this engine is the most durable and most economical to operate than just about anything out there for this pourpose. I have some wind generator motors also but no finances to get them up in the air as yet. I also need 12 150 watt solar panels but it takes money to buy them and that is something I don't have!!

Thanks for your help.
DaddJohn