[scottj]

We always use Fel Pro with the stainless compression ring and depending on cu. in. we run 13.5:1 to 15.5:1 at near 800 HP. Like Andy said, we also silicone the water passages, studs, and washers or else aluminum motors WILL LEAK coolant until they reach temp. Iron blocks don't move as much as aluminum so the silicone is more of a precaution than a necessity but a very good idea none the less. Use sparingly for the reasons Excaliber stated.

Be aware when mocking up that proper squish clearance is important to making max power as well as being important to resistance to detonation. Increasing the squish to much more than .040" (for steel rods) by using a thicker head gasket could make the engine more likely to detonate.

Scott