I have botha 1979 B-700 (bus) that is running propane, and a 1966 F-250...if I go with propane on a re-built 390 what kind of compression, and or specs should I be looking for?

 

if you are going to run propane only, then my logic tells me since propane is roughly the equivalent to 114 octane gasoline(minus some btu's), you should run about 10:1 compression to optimize the available propane btu's. i would also go with an advanced curve distributor to further optimize the propane. an rv grind cam would be about the highest lift and duration i'd go ( from talking to other guys with more experience with propane only ). they told me propane doesn't like a lot of cam. hope this helps...

 

i would have to agree with 65superduty. Im a diesel engine mechanic, and you need higher compression in order to even run propane. Its not just getting into your engine. Im tring to find out myself how complex it is to run propane in a 80's ford. Seen it done before at about half the cost

 

hmm, i've been told 14 to 1 is the compression you should look for when running propane along with a different set of valves. Higher output ignition is a good idea.