Ilfochrome printing

I've been trying to print this material using my Beseler 45 Universal
enlarger Head without success. Filtration is Y17, M00, C10. Recommended
exposure time, according to Shule's Book "Cibachrome Printing", would be 22
seconds as a start for an 8X10. However, following these guidelines, I get
an exposure which can hardly be seen - so dark!! (I develop with the Jobo
CPP and Ilford Ilfochrome Chemicals, as per their instructions). Leaving
the filtration (colors) alone, I then made several other exposures with the
following times: 50 seconds, 70 seconds, 90 seconds, 110 seconds, lens set
at f4. Needless to say, the prints got lighter so you could see whats on
them, however, I still could use an additional 20 seconds exposure - makeing
this 130 seconds total for a "normal" print. My questiion is this: Is this
normal - seems to me to be way to long of an exposure for a 8X10 print! I'm
no darkrooom expert, but when the slide starts to buckel at about 40 seconds
due to heat, something has to be wrong. Appreciate any responses.