Gunson's Gastester

[M Fawcett <m.fawcett@verizon.net>]

Hi All,
My wife bought me a Gunson's Gastester for Christmas so thought I'd give it a 
try. When I read the booklet that comes with it, it states that the CO level 
should be set according to the manufacturers requirements. Does anyone know 
what the percent of CO should be for a 1960 Big Healey.  The booklet suggests 
that the range is from .5% to 4.5%. This seems a little wide and I'd like to 
narrow it down. Any help is appreciated.

Mark Fawcett