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Converting Deisel to gas

Discussion in 'The Garage' started by MuddNutz, Jan 25, 2004.

  1. MuddNutz

    MuddNutz Registered Member

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    Since the search function is down, I will ask here. What is involved in converting a truck with a deisel to a gas 350?
     
  2. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Depends on which gas 350. If carbed, just swap the motor and flush the diesel out of the fuel system. Make sure to get the engine harness, accessories, and brackets. Throttle cable is also different as are the radiator hoses. Just small stuff like that. You also may want to change converters because the diesel is a very low rpm stall. That’s about all I can think of. TBI/TPI/Vortec etc. have other issues but aren’t that hard. I did TBI with my swap.
     
  3. JDBlazer454

    JDBlazer454 1/2 ton status

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    [ QUOTE ]
    Depends on which gas 350. If carbed, just swap the motor and flush the diesel out of the fuel system. Make sure to get the engine harness, accessories, and brackets. Throttle cable is also different as are the radiator hoses. Just small stuff like that. You also may want to change converters because the diesel is a very low rpm stall. That’s about all I can think of. TBI/TPI/Vortec etc. have other issues but aren’t that hard. I did TBI with my swap.

    [/ QUOTE ]

    I never changed my harness just zip tied up the unused wires and tapped into the ones I needed.

    As for front end brackets if you are going from 6.2 to 350 all the front end brackets and acc. will all bolt right up including the hydrovac brakes.

    Remember to change the diesel fuel filter on the fire wall and to flush the fuel system of all diesel very very well. I had too much residual diesel left in my system and it blew the new 350 in 2 days so be very careful and double check everything.

    Good luck.
     
  4. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    I just suggested grabbing the harness to make things simpler and neater, especially if the donor is EFI or ECC. In fact, I switched out the under dash harness too which made conversion to TBI a snap plus it got rid of the diesel idot light cluster. I also had the 12V/24V hybrid and military equipment so I got to eliminate all that noise too. Sorta thinking about bringing back the 12/24V though just to power a 24V winch...

    Hmmm, not sure on reusing those brackets, mine were completely different. Maybe it depends on models since brackets did change even on gassers depending on the model? <shrug> Either way, as long as you can get the accys to line up with the block pullys and with the right accy pully type/size, it should be fine. But I did use the hydro-boost sagi pump on my TBI 350. But, the ham can is thicker than the non-hydro boost pump so the bracket had to be modified slightly. You could also "T" into the return line and swap the relief valve to use the normal gasser pump, but you would loose some volume.

    Also, mine did not have the filter on the firewall, it was mounted on the engine. Not sure if that's normal, CUCV related, or PO related. I don’t remember much about it since it was dead and I left the carcass with the PO (him pulling it out and keeping it was part of the deal, I didn’t want it. /forums/images/graemlins/laugh.gif )

    As for care in flushing the system of diesel, running with a little diesel in the gas shouldn't cause anything worse than bad gas type behavior. Small amounts of diesel should hardly be noticeable at all. Worst case it should run rough and stall or not even start. Can't imagine how it would hurt a motor. /forums/images/graemlins/confused.gif
     
  5. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]
    I had too much residual diesel left in my system and it blew the new 350 in 2 days so be very careful and double check everything.

    Good luck.

    [/ QUOTE ]How the hell did it blow the motor up? /forums/images/graemlins/confused.gif A friend of mine accidently got a couple of gallons of diesel mixed in my tank when he borrowed my K5 and my 406 just smoked like crazy and pinged bad until we siffened it all out. Did the detonation blow the motor up? what the hell happened? /forums/images/graemlins/ears.gif
     
  6. JDBlazer454

    JDBlazer454 1/2 ton status

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    I think we had more diesel left in the tank then we thought, it was totally a stupid mistake on my part and I had only put in 5 gallon of new gas when we fired it. Well it was running overly hot and massive pinging and went 8 miles round trip before coming up the hill home and 4 driveways away blew it sky high. This was my first and only diesel to gas attempt and will probably be my last.

    The fuel filter on the firewall was something stock on my stock 82 'burb and I have seen it also on my neighbors stock 80 2wd once upon a time diesel p/u (now has an Olds 350). I just remember it looked like an oil filter and had to look it up in my Chiltons to figure out what it was.
     
  7. bigburban383

    bigburban383 1/2 ton status

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    You must lower the compression. Probably changing the heads out.
     
  8. RATAH

    RATAH 1/2 ton status

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    ljones 3 post and already a member CONGRATS,
    welcome to CK5 the best chevy site on the net,
    my ? is why do you want to go
    from deisel to gas?
     
  9. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]
    You must lower the compression. Probably changing the heads out.

    [/ QUOTE ]What the heck are you talking about? /forums/images/graemlins/confused.gif
     
  10. MuddNutz

    MuddNutz Registered Member

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    I am looking to convert because the truck has no motor in it right now, but it had a 6.2 in it from the factory. I like the 350 and I don't know anything about deisel so I want to convert. Another problem just came to mind though. I live in a county that has emissions testing and I dount that a 350 gas would put out emissions in the deisel emission range so I doubt it will pass. Anyone have any thoughts about this emission delima?
     
  11. ben427

    ben427 1/2 ton status

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    Do they smog the diesels?? most places dont.
     
  12. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    not knowing anything about something to ME is a reason to get one. the diesel is better MPG, lots of mods out there for them, and more TQ. you can run taller gears for any type of wheeling. about the only thing a diesel isnt good for is mud.
    im looking for a diesel. it will be replacing my TBI setup i have now.

    oh, and as for the diesel emissions.. i properly tuned diesel will burn cleaner than a gas motor.

    anywho, welcoe to the board, and thanks for paying up so soon. hope you get a lot out of it. i know i have.
    Grant
     
  13. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Most likely you will never have to emissions test it. It's already registered as a diesel and should be exempt. If you never tell them you swapped in a diesel, they will never know. At least that's how it is here. /forums/images/graemlins/laugh.gif
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    Emissions requirements vary state to state. If you get a sniffer, you'll fail. The ONLY reason they started testing diesels (after gas testing had been going for a few years apparently) in this state was to catch people that were converting diesel rigs to gas so they wouldn't have to go through emissions.

    It's legal to do the swap here (and again this can and likely will vary from your state) but you have to swap out things like the fuel fill neck, any stickers indicating diesel, and the fuel gauge. After doing this, you get it inspected, and the title is changed to reflect a gas engine.

    As long as the engine was available in the rig (350, 6.2, 4.3, etc) the year yours was made, it's a legal swap, and as long as it's *as new or newer* than your truck.

    All emissions components must remain in place from the donor vehicle in most emissions testing areas when doing an engine swap.

    Again, these are kind of generalizations. Every area is different, but many share similar rules.
     
  15. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    In short it's a PITA to do.
     
  16. dyeager535

    dyeager535 1 ton status Premium Member

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    In my area yes. If they weren't required to pass emissions, no. (of course, those requirements can and do change, and people move)
     

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