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Small-Block 400 Cooling Tricks

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This 1003 high- performance Fel-Pro head gasket features larger 7/16-inch coolant passages (a) that will produce greater coolant flow to prevent excessive heat buildup between the center cylinders. The high-performance Fel-Pro gaskets also reduce coolant flow in the indicated areas (b) to help redirect the coolant between the center cylinders. If necessary, you may have to drill a 7/16-inch hole (c) in the block to increase coolant flow between the center cylinders. Only do this when the engine is completely disassembled to prevent iron drill chips from damaging the engine.

Drilling for Water Fel-Pro added this 7/16-inch center-cooling hole since it is present in all production iron heads but may not be present in all cylinder blocks. If there is no hole in your block, you can easily drill the soft cast iron to create the water passage. This is not as difficult as it sounds, and the head gasket can be used as a template to correctly locate the position of the hole. We’d suggest drilling a small, 1/4-inch pilot hole first, followed by a 7/16-inch drill bit. Remember to remove the gasket before drilling.

How many of you take the time to neatly open a new package of anything? Now how many of you actually take the time to glance or (dare we say) read the directions that came with your new package of anything. Yeah, we didn’t think so, but that’s OK because we're generally guilty of the same thing. So imagine our surprise when we did take the time to look at the Fel-Pro gasket installation tips for our small-block.

According to Fel-Pro, most head-gasket failures occur between the two center cylinders. This is because the small-block Chevy locates two exhaust ports adjacent to each other between the two center cylinders. This concentrates a tremendous amount of heat in this one location, which can cause the head gasket to fail.

In order to redirect additional coolant between these two center cylinders, Fel-Pro added a large 7/16-inch hole just below and between them. In addition, the center coolant hole above the center cylinders was enlarged to 7/16 inch. To ensure that additional coolant flows through these holes, Fel-Pro also restricted water flow through the lower holes between the center and outer cylinders. Combine these changes with a high-performance water pump, such as the excellent piece from Edelbrock, and you have a much more efficient cooling system.

These modifications to the head-gasket cooling system are only found on the performance line of Fel-Pro head gaskets. The stock replacement head gaskets feature the normal coolant hole passages. If you are considering more compression, a supercharger, nitrous, or a turbo, these high-performance gaskets with the redirected coolant passages are probably an excellent choice.

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