Searched several topics, but never saw anything that completely answered my question. I have a 390 that drinks propane. I would like to ditch the propane and go back to gas.(I am thinking it was a conversion, not an origional setup as it does have a gasoline tank, just no lines). What all is involved? Re-plumb the gas, change out the intake and carb and rock and roll or what?

Thanks.

 

hey tank,i have done about 5 of these swap's back to gas from propane.they were all on gmc 350's but it's the same. you need to replume your fuel line's,make sure there is no old gas in the tank,i had one that was half full.you will have to put on a new fuel pump because your's is either gone or been sitting for to long and wood be no good. you do not have to replace your intake just your carb.,and if your fuel pump is gone you will need a fuel pump push rod.you may have to adjust your timing.it's not as bad as it seem's,good luck,and have fun/scott.

 

Have you seen any problems with how the engine holds up after the switch back? I have a neighbor who did this whole thing on one of his trucks, But we don't get along so much, so asking him is not a great option. I did hear however that when he did his, he also opened up the motor just to check everything out, and everything looked perfect, clean and untouched. I'm assuming this had to do with the burning properties of propane? Have you seen this at all?
To save myself the grief, I had thought about getting a new gas tank, and running an electric fuel pump, sound good? The truck will be free if I go get it so dropping a couple bucks into the swap is not a problem.

 

FYI A properly adjusted and set up lp fuel system should get real close to what the engine would get on gasoline. That being said its not hard to de-convert the engine you just need to repair/replace all of the missing gasoline items (carb,fuel pump etc) and have at it. You might want to have your distributor curve checked because if it was originally done right and its dedicated LP it should have been recurved. Any questions you can e-mail me.
Good Luck

 

Sounds like I'll do it then, if thats whats involved. Gasman, I will let you know when I get my hands an the truck what I find.

ps- If I had a method of filling it here at the ranch, I would consider leaving it propane, But with no way to fill it, and all the free gasoline I can guzzle from the ranch tanks, Its just more economical in the long run for me.

 

I am trying to convert a f-250 back to gas. Could you send me pics of your engine. all of the wires have been cut and we are at a loss as to how to proceed.