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Thread: bosch platinum spark plugs

  1. #1
    Join Date
    Jul 2009
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    Default bosch platinum spark plugs

    I have read on the forum that he autolites or ngk are the way to go. Has anyone used the bosch platinums?I have a 345 with a msd ignition.

  2. #2
    Join Date
    Feb 2009
    Location
    Aiken, SC
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    2,423

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    Quote Originally Posted by mthebull View Post
    I have read on the forum that he autolites or ngk are the way to go. Has anyone used the bosch platinums?I have a 345 with a msd ignition.
    The IH engine is made to run at a lower temperature than a more modern engine. The autolite or NGK seems to work better. That's from a stock ignition system, though.

    With the MSD, it might not matter due to the higher voltage and multiple spark. It's likely you could just run anything that would screw in. I used to run the MSD gap at .050 with Autolite 85 plugs with no problems, but I didn't gap them any higher because I was concerned that the tips would weaken if I bent them too far open. I had to replace the MSD about every year to 18 months, and they were charging 55 bucks to just replace it. I would just swap in my spare, send in the other one. I found that to be annoying, so I stopped using them.

    On my dump truck and my school bus, the deeper Autolite 303 plugs were recommended, with the spark deeper in the combustion chamber, but I never could find any, so I used 85 with no problems. I suspect using the 180 degree t-stat is the reason for the specific plugs.
    Allan E.
    Curmudgeon Extraordinaire
    Charter Member, Old Hippie IH Club
    Old fashioned binder freak

  3. #3
    Join Date
    Jun 2009
    Location
    Little Rock
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    I assumed that Platinums would be the way to go in my 345 w/points because they last longer...this was not the case at all. I was told by an older Scout owner that this was because the motor was designed to run on copper. I ran AC Delco in there and actually noticed a difference in responsivness.

  4. #4
    Join Date
    May 2009
    Location
    Litchfield, Ne
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    1

    Default bosch platinum plugs

    I put a set in my 392
    I am very happy with their performance

  5. #5
    Join Date
    Feb 2009
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    19

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    Quote Originally Posted by 73ScoutDude View Post
    I assumed that Platinums would be the way to go in my 345 w/points because they last longer...this was not the case at all. I was told by an older Scout owner that this was because the motor was designed to run on copper. I ran AC Delco in there and actually noticed a difference in responsivness.
    Platinum plugs don't require as much voltage to fire, so the spark is weaker when it occurs. If the ignition system isn't generating enough voltage to fire ordinary plugs reliably, then platinum plugs will offer some improvement.

  6. #6
    Join Date
    Jun 2009
    Location
    Little Rock
    Posts
    40

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    Thats good to know. I assume mine is working fairly well considering I replaced the distributer, alternator, wires, plugs battery and batt cables. The only thing I havn't replaced is the coil. Allen E. has posted several times that if a coil works its good, if its broke its broke. So it'll be in there til it dies. With the copper AC Delco's my 345 seams to run smoother than with platinum. In a modern vehicle like my ford I run autolite platinum because thats what the owners manual reccomends, in my toyota I run NGK iridium's. They last forever and out perform platinums all day long. I thought Platinums would kick a** in the scout, but trusty old copper won that battle.

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