235 straight 6 running hot....DRIVING ME NUTS!!

Is the anti-freeze rusty, could engine need flushed? If it isn't coming out of radiator are you having to add any periodically? Could mean it's being puuled into cylinder during inake stroke.
One way to check for a bad head gasket is to fill radiator up to neck, start motor and watch for bubbles getting increasingly larger and more frequently. Engine should be cold of course.
Is there any reason your not running a stock housing? I can't lay off the thermostat need because it caused me to go through everything before I checked the most common. Even after a greybeard told me to change it.

 

http://www.jalopyjournal.com/forum/showthread.php?t=651001

link shows a picture of and original housing,,,

why cant you go back to what is supposed to be on there?

 

I had a similar problem on my 235 55 chevy. The radiator was crudded up inside. Chased my tail on that for a couple of days.

 

folks hold the phone till Jr
tells us about , the mounting of , the change away from ,
a housing that CAN hold a thermostat?


http://www.jalopyjournal.com/forum/showthread.php?t=651001

 

My 31 had a thermostat I put in on the top rad hose,worked great,staged the coolant long enough to keep the solid lifter 289 cool...two solid pipe flanges,2 nutz and boltz,washer,gaskets(2)...done like dinner.

 

in 1970 i built a water pump system for
the current drag car...
it was a one only configuration that would only
pump the fluids when i flipped the on switch.
and it was set up for some of the fastest 5 gallon water exchanges
in the pits.


POSSUM JR where Are you we want to help here...

he needs to tell us all about the modified (lack of) thermostat housing....
so HOLD THE PHONE TILL HE gets back in here

 

Water pumps cavitating. Change out that bottom hose. Or put a coil in that one.

 

POSSUM JR

Have you tried to take the upper radiator hose off the radiator, get a water hose, seal it inside the upper radiator hose turn it on full , see if you get good flow out of the upper radiator hose connector(since you don't have a thermo)....

boooooob