I know this is long, but some history...
Installed a long block from reputable frim. Ran well through the fall. brought home from hunting camp for the summer, and to do a few modification to elecrical system. Started running hot. Radiator was cleaned and new water pump and thermostat during new block install.
Have flushed cooling system, installed new fan clutch and additional auxillary electric fan.
Tested radiator cap and radiator, no leaks. left tester on radiator and started motor, pressure in radiator begins to build.
Not a large amount, several pounds per minute. Pulled each plug with the thought that if blown / leaking headgasket, could determine which cylinder was leaking, pressure built, no matter which plug was pulled.
Any ideas on problem,
Thanks in advance,