picking a cam for a propane motor is the same as a gas motor(but let your cam grinder know it's propane, as he might have a "trick" propane grind)i run 12:1 comp on my street ,propane, fuelled motor(tripple mixers and duel converters)no problems at all(make sure the timing has no more than 30'total advance)you can see my rod(aussie 265 hemi inline six-277 cu in)on http://members.optusnet.com.au/~c_s_rod_and_custom/gallery.html