[TR] TR-4 Rear oil seal modification

[Randall]

> I've had two professional engine builders tell me that the secret to
> getting
> the scroll type rear seal to actually seal is to machine the aluminum seal
> plates so as to reduce the clearance between the aluminum scroll and the
> crank to .006 to .008 from the standard .010 - .012.

All of those numbers seem huge to me.  I've got an old note from Hardy
Prentice saying the setting mandrel shown in the workshop manual is marked
.004" oversize (should be 2.818" instead of the given 2.822").  ISTR Greg
Solow and others agreed.  But I thought that gave a radial clearance of
about .003" between the crank & seal (with the crank centered in it's
bearings).  And he didn't mention having to modify the seal to achieve that.

Hardy also gave a method to "make do" without the mandrel, by wrapping the
crank journals and scroll with sewing thread to take up the clearances.

Randall