| 摘要 |
A core portion (47) that is used to hold an upper water jacket-forming core (45) and a lower water jacket-forming core (46) with a predetermined distance maintained therebetween includes holding core portions (48) and distance maintaining core portions (50). The upper water jacket-forming core (45) and the lower water jacket-forming core (46) are split from each other at the holding core portions (48). Communication passages that provide communication between an upper water jacket and a lower water jacket are formed by the distance maintaining core portions (50).
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