I figured smaller valves 1.84" intake, ???exhaust, were probably better for low rpm towtruck. The cam was milder than old one (now 204, 214 duration) because more cooling time on seat required for propane. It really upped the compression, maybe too much for heavy tow uphill on propane, but okay for these parts.gerry said:dont 305 heads flow very poorly?? how is it for power now???
crewcab454 said:just a thought putting a set of new heads on old engine can sometimes weaken the bottom end, but if it runns good now maybee o.k. just a thought
gerry said:you can run as much compression as you can get, with propane and no detonation problems...
Gerry you propane expert you. LOL!
For light-duty passenger-car applications, compression ratios as high as 10.5:1 can be used without incurring detonation (on propane). For light-duty pickups that see only occasional hard work, 10:1 is a good ratio. For heavy-duty or extended high-rpm use, stay down around 9.5:1 or 9:1 compression.