240d starts hard now that engine is in new car?

I swapped the engine out of my beat 1975 240d into a nicer body about 2 weeks ago; everything has been great except that the engine is much harder to start now. When I did the swap I made sure to keep everything possible with the engine, so starter, glow plugs, fuel and injection pump, etc. etc. all were originally on that engine. The glow plugs still work and appear to reach the same temperature in the same time, the engine cranks at the same speed as far as I can tell. The battery terminals are clean. But for some reason I have to glow for twice as long AND crank for two-three time longer than before (when the engine was in the other car). Any ideas? My only thought is that I need to re-adjust the fuel injection/intake linkages or something... or maybe the battery that came with the car isn't as good as the other battery. It is the correct battery however (the previous car had an incorrect, much smaller one) and puts out 13 volts when charged.