Relief Valves

[Thomas Wiencek <wiencek@anl.gov>]

I have heard that there are two types of Series V relief valves.  Early ones 
(not so good) and later ones (improved).  Is there a way to tell the difference 
without having to destroy an engine?  Also, were there any problems with the 
1600 brass relief valves or changes (improvements) in design?  Thanks.
Tom