R;
The seal MUST be pushed against the crank, no matter what brand you use. This is done by the method I explained. It's just not tight enough around it, is all.
I first learned this from an "old time" mechanic that worked mainly on the 216 in the 30 & 40s in about 1959 when I was a 'teenager'.
Later on, the crank was machined (as mentioned) to assist in oil control for the "Hi pressure" engines (216 was 15#).
The only other thing (to cause leak) is the bearing clearence which I'm sure you've checked. The crank grinder would have checked (run out) in the grinding process.
Packing the seal in (as mentioned) is okay too.
I have seen only one engine with the offset seal installed (as Walt mentioned), but don't know how this is done. It may have been a (in frame) replacement.
Check with Beck's and see what they say etc.
Good luck.
