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EJ257 Build

Practical Engine Building

Discussion and questions related to the course Practical Engine Building

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Hi Guys,Andre,

I am presently rebuilding a EJ25 motor for around 1000HP. What’s your recommended main and rod bearing clearances? Was thinking of the rods set to .002-.0025 and mains .0015-.0017. The motor was built before with .0026 mains but oil pressure got low (45psi) at high rpms.

I'd say your clearances are in line with where I'd be setting them. The thing that is easy to overlook with the main bearings is that these will grow as the cases heat up and expand. This means your actual hot running clearances are nothing like what you measure cold on the bench.

Thanks for your response Andre much appreciated