Intake manifold removed on 302 with 351 heads

[BayStYAt]

I remove the intake and found one of the ports was purposely sealed. I removed it in preparation for new gasket. The port in the intake that is blocked is a super dirty oily mess. Please explain why this is done.

thanks

[Nitekruizer]

If you mean the little port in the middle of the head, that is the heat crossover, which is basically for faster warm-up times. Usually there will be a heat riser valve on one of the exhaust manifolds. It causes the hot exhaust to flow through the heat passage in the intake manifold while the engine is cold. The heat riser opens as the engine warms and most of the exhaust then flows out of the exhaust manifold normally, instead of through the heat passage and under the carb. When using an aftermarket performance intake, a lot of guys choose gaskets that block the heat passage to keep the intake charge cooler, especially if we just drive them during the summer anyway.

[BayStYAt]

If you mean the little port in the middle of the head, that is the heat crossover, which is basically for faster warm-up times. Usually there will be a heat riser valve on one of the exhaust manifolds. It causes the hot exhaust to flow through the heat passage in the intake manifold while the engine is cold. The heat riser opens as the engine warms and most of the exhaust then flows out of the exhaust manifold normally, instead of through the heat passage and under the carb. When using an aftermarket performance intake, a lot of guys choose gaskets that block the heat passage to keep the intake charge cooler, especially if we just drive them during the summer anyway.

Awesome thank you. I wish I didn't remove it now. I will replace.