1988 plymouth Voyager 3.0 oil leaking?

I am doing a job for a friend, I had to pull the engine and , change the engine and rebuild the transmisson for her. The problem is the new engine has a VERY bad oil leak coming from behind the harmonic balancer. While it was out I change the crankshaft seal and lubed it properly because it had the oil leak before it was pulled from the other car. Imagine my level of fustration when I finally get it all back together and start the engine only to have it pouring oil like I did nothing at all! When you start the van initially there is no oil drips.. in about 10 seconds tho it starts a steady drip that would roughly equal 1 quart to every 5-10 miles worth of driving. I know I put the seal in correctly but this one has me stumped. Any ideas? Ive seen bad camshaft leaks before but this is alot worse.. I can take a look tho. Thanks for any advice with this