Battery not strong enough for new engine

[QuantumMotorsports]

Have you grounded the motor well? You need to be sure that you have adaquate ground straps. One to the block and one to each head is what my machine shop told me. I would sand the paint off where the ground strap contacts the engine as well. Other than that, try priming the oil pump. Find a socket that will fit the oil pump shaft, then chuck up a ratchet extension in a variable speed drill and put the socket on the extension (I would tape it on also just in case) then use that to turn the oil pump and get some oil flowing. That might help. A new engine should not be very difficult to turn. Is the starter good?