Sounds like you got the wrong thermostat housing.... The thermostat fits in the housing,
Thermostat housing, thermostat, gasket, water pump housing, in that order.
Use like a 170* or a 180*
Look up model year 1970 should work and be the rite size.
Also use like a 16LBS radiator cap with a good recovery bottle
Keep us posted..

 

You say its has an Edelbrock manifold. Are you sure its a 440? My t-stat is not installed in the manifold.

 

440 -

5 brings up an interesting point. 440s have the T-stat on the water pump housing, not the manifold.
Sounds more like a small block, and yes, the right t-stat should fit.

BTW - even though it goes against common wisdom, if the engine doesn't over heat (or take too long to reach operating temp), then you might not need one. While I don't agree with that practice, it's been done too many times to argue about.

Archer

 

Thanks Guy's I Fixed my reply... Good catch....

Good Gosh,,,, I'm Slipping.....

 

T-Stat installs in the T-Stat housing not the manifold. Go with a 160 T-Stat is you are running a Cast Iron Block and Cast Iron Heads, for Aluminum heads go with a 180.