An abstraction of protocol differences in ad hoc networks is necessary for general-purpose use. The existing studies usually assume an indirect connection via the backbone network when there are different protocols used in ad hoc networks. That cannot take advantage of ad hoc networks, called "infrastructure-less". Moreover, the demand of communications with allowable delay such as M2M has been increasing recently. Ad hoc networks also expect that of routing method considering the delay. However, there has been few studies about that. Therefore, in this paper, we consider a direct connection between heterogeneous ad hoc networks by a protocol translator. Each flow in the networks determines an allowable delay. We then propose a method that maximize the number of flows satisfying the delay constrain by an optimal routing. Finally, we compare the proposed method with the optimal solution and analyze it by the simulation.