Originally posted by techinspector1
I've resisted using 400 blocks because of the cooling problem.
I hear you Inspector;

But I have had zero cooling problems with my 400's. I use a four core rad, dual electric fans, but best of all, is the four corner cooling Edelbrock came out with. These newer intake manifolds are the ticket. I for the life of me do not understand why anyone would use OEM cooling technology anymore.

These intakes have four threaded water bosses and what I do is plumb the rear two bosses to connect to the front two with 5/8 heater hoses and brass fittings. Then before I install the intake manifold, I install a restriction plate in the water return holes with a maximum of a 1/4 inch hole diameter in these two front bosses where they mate with the heads.

This forces the majority of water to be directed past all cylinders and exit out of the rear of the manifold, then through the heater hoses which are connected back to the front ports. In effect, you have created a low water pressure area in the thermostat housing area and by doing so, the water from the rear of the motor has priority over the front.

This permits the engine to have equal cooling over all eight cylinders. If one leaves it in the original configuration, the cool water exiting the water pump, is immediately allowed to exit into the thermostat housing and back to the rad. True, some cooling will still occur, however the majority of the cooling is for the front two, perhaps four cylinders. In this configuration, the front cylinders might well be 190 degrees, but what about the back four? I can only imagine if one installed a sensor at the very rear and the very front, that there would be at least 40 degrees difference noticed.

From all the engines that have failed that I have heard of where heat was a factor, it is always one of the back four pistons that bit the dust. The problem, when the water is four pistons deep, and the cooling is rushed past the front pistons only, the deep waters just don’t have any ability to exchange the heat. Still waters run deep.

[i]
A 350 block with a turned-down 400 crank is the answer for me. [/B]
As for the turned down journals of a 400 crank to fit a 350 block, that system isn’t worth the effort anymore. Not to mention, those cranks are 30 plus years old and metal fatigue becomes a factor. I have found that the new off shore grinds are as cheap as re-grinding an old 400 crank, plus they are 50 percent stronger, maybe more. I would never use an old crank in a motor which has to dish out more than 400 horsepower.