pg_dumpall pg_restore

Ok this should be simple but I am missing something here.

Yesterday I upgrade to 7.4 before I do that I run

$pg_dumpall > /tmp/pg_keep

When I try to restore off this file I get
pg_restore: [archiver] input file does not appear to be a valid archive

So I tar the file and it appears to be a valid archive now..
Now when I try to restore I get the error:

pg_restore: [tar archiver] could not find header for file toc.dat in tar
archive

What am I missing here? Or is my dump just not valid and I am out of luck.

Btw I did the dump with the 7.3 tools and now am using the 7.4 restore if
that makes any difference.

Rob