The 383 in my Fury conv overheats as sson as I drive the car at more than 60 mph. If the car is standing, it doesn't seem to overheat. I have checked the water/ antifreeze, and it's very dirt. I tried to wash cooling system with a garden hose, but no luck. Car has about 40.000 miles, has been standing in the open for many years and has Always had this problem. I left in storage for a couple of years, and now problem has gotten worse. Radiator is new, 3 row 26 inches, new Thermal fa, shroud and 7 blade fan. Advance is correct. No water in the oil. I am pretty sure the engine is clogged with rust and mud in the water passages, as water is rusty and dirty. How do I clean the water passages without hot tanking the engine? I was thinking about removing freeze plugs on the sides of the block. Any other idea?
Thank you

Pulling the side plugs and improvised tools and water to dig or scrape the junk out works. The radiator may be plugged also by the circulating dirt even though its not old. Inspection by a radiator shop and cleaning if necessary should fix it.

For a really good flush, I rig up a garden hose adapter for the top radiator hose. 1 1/4" pipe (iron or PVC) seems to be about the right size. Put the hose on with stat removed and let her flow. Sometimes I also rig up a "T" hooked up to a compressed air line. Get the block full of water then turn the air on. Lots of water, air and dirt will come out the WP inlet. Repeat until it comes out clean.

Unscrew the 2 plugs that are in the forward part of the block.They are right behind the motor mounts.Ill bet they are pluged solid.Use a screw driver to open them.Then put a hose in the top of rad and let her flush.I run the motor while its flushing also.Take out the stat first.Then flush thru the heater hoses also.Rocky

Also check you lower radiator hose to be sure that it is not collapsing due to the water pump suction at high speed. Often times, these hoses will have a metal coil inside to prevent this from occurring.
John