"XTREME" BIG BLOCK
HEAD PORTING 101
OK Class, today we're going to cover how to port your Big Block heads for "XTREME" performance.
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Above photo shows much I raised the intake ports to increase flow on these Big Block heads. Notice how the port on the right is now 0.125 taller than the port on the left.
After you fill the crossover passages with Aluminum you have two choices on how to you can shape the aluminum. You can just narrow the valve guide boss in a circular shape and then shape the aluminum so it's round and bend it into the floor. Or you could shape the aluminum so it will look like the end exhaust pockets by shaping the exhaust valveguide bosses into a teardrop shape before you fill the heat cross over passages and then grind out the aluminum so it blends into floor and valveguide bosses as shown in pictures below. Be sure to shape the valveguide bosses like a teardrop before you pour the Aluminum into the heat crossover passages. Either way will work and the teardropped shaped would flow slightly better but it's a lot of work and it could break off do to differances in the heat expanding rates between Aluminum and cast iron over time.
Having the exhaust divider brazed up will help exhaust flow. You'll have to shape it with your die grinder or dremel tool and then have the entire exhaust surface of the head surfaced so it's flat as shown in the photo's below.
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