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  1. #1
    Petty Officer 1st Class Spivy30's Avatar
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    Default When was the switch from leaded to unleaded fuels in marine power plants?

    I just bought an older boat a 68' starcraft and it got me thinking about the switch from leaded to unleaded fuel and I wondered when this took place in marine applications. My boat runs perfectly fine on pump gas but I was just curious when this took place? I'm a younger guy (21) and this was before my time. Im also curious what had to be done to make older engines run on unleaded fuel? I've seen lead additives for cars at auto parts stores and kind of always wondered.

    Thanks for helping with my curiosity

  2. #2
    Supreme Mariner bruceb58's Avatar
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    Default Re: When was the switch from leaded to unleaded fuels in marine power plants?

    Unleaded fuel started to be available around 1975 or so. Engines manufactured before that, including marine engines, did not have the hardened valve seats that you need to run unleaded gas. That being said, I would just run your engine until you started having compression problems and then have a valve job done on your existing head to bring it current. May never need it since marine engines run a lot less hours and revolutions over their lifetime compared to an automotive application. You may never need the valve job.
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  3. #3
    Petty Officer 1st Class Spivy30's Avatar
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    Default Re: When was the switch from leaded to unleaded fuels in marine power plants?

    Alright thanks for the info I always wondered about that.

  4. #4
    Fleet Admiral HT32BSX115's Avatar
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    Default Re: When was the switch from leaded to unleaded fuels in marine power plants?

    May never need it since marine engines run a lot less hours and RPM compared to an automotive application. You may never need the valve job.

    Yeah, my previous 66 Marktwain (150 Mercruiser that Dad bought new) got unleaded fuel for most of it's life!

    It NEVER had a valve job and ran good those 39 years until I sold it in 2005.


    You won't need any snake oils in the gas..... Just gas it up and go boating!!


    Cheers,

    Rick
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    I use xxx oil and have never had a problem........
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  5. #5
    Commander thumpar's Avatar
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    Default Re: When was the switch from leaded to unleaded fuels in marine power plants?

    I was a senior in high school the year that leaded gas was banned. My buddy had VW bug and was worried about unleaded. It ran fine until he sold it. My dad has a 66 mustang he changed the valve seats on but only because he was redoing the head anyway.

  6. #6
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    Default Re: When was the switch from leaded to unleaded fuels in marine power plants?

    Quote Originally Posted by HT32BSX115 View Post
    Yeah, my previous 66 Marktwain (150 Mercruiser that Dad bought new) got unleaded fuel for most of it's life!

    It NEVER had a valve job and ran good those 39 years until I sold it in 2005.


    You won't need any snake oils in the gas..... Just gas it up and go boating!!


    Cheers,

    Rick
    Yup, our 76 Mark Twain (75-built 351w) didn't have the hardened valve-seats either and we never had an issue with unleaded fuel. I doubt most people use the lead substitute in anything anymore.
    1976 Mark Twain 200VBR w/Mercruiser 233 (Ford 351w) "Heart & Soul"

  7. #7
    Fleet Admiral HT32BSX115's Avatar
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    Default Re: When was the switch from leaded to unleaded fuels in marine power plants?

    Yeah, when you consider all engines out there that were run on propane until they just completely wore out, it sort of throws cold water on the "gotta have lead to lubricate the valve seats" song-and-dance!!!
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