I have a 400 crank in my MTI built 409 c.i. Lt1 stroker. The rear main seal leaks apparently due to the adapter which is necessitated by the combination. The machine shop who has the motor now claims that a "re-machining" of the area and putting on a new adapter will solve the problem. This scenario is over my head, so I don't have any way of gauging whether or not they are honest. Hopefully you guys can offer your $.02

 

Here's what I know about the situation... If the seal adapter is not installed correctly, it may move in relation to the crank and that'll cause leaks. Most machine shops use an arbor that positions the seal adapter, they then drill and ream the adapter and block at the same time. Then they install alignment dowels in the block and install the adapter. If installed properly, it won't leak.
Now your problem could be a misaligned adapter or it could simply be a seal. I'd want to see the seal before having them do any work. Hope this helps a little.

-Mindgame

 

Did you call Jayson by chance to see what he had to say about the whole thing?

Steven