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  1. #1
    Petty Officer 2nd Class Merc4ever's Avatar
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    Default 4.3 Mercruiser Thunderbolt IV base timing

    Most of us know the Thunderbolt V has a purple wire that needs to be grounded to set the timing in order to stop the auto advance. But what about the Thunderbolt IV on a 4.3 Mercruiser? I'm trying to time it right now and can't find how to put it into base timing mode. The Mercruiser service manual doesn't mention it in the timing section and I know there is no purple wire to ground on the Thunderbolt IV.

  2. #2
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: 4.3 Mercruiser Thunderbolt IV base timing

    The Thunderbolt IV system does not get put into base timing mode.
    Don S.


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  3. #3
    Moderator Bondo's Avatar
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    Default Re: 4.3 Mercruiser Thunderbolt IV base timing

    Ayuh,.... The T-Bolt IV is simply attach the timing light, point,+ set....
    Any Grease is Better,..... Than No Grease at All.......

  4. #4
    Petty Officer 2nd Class Merc4ever's Avatar
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    Default Re: 4.3 Mercruiser Thunderbolt IV base timing

    Duh... I just spent 2 days lookin for the damn thing! I should have just visited iboats first. My manual covers several years but doesn't specify the Thunderbolt IV doesn't have the wire.

  5. #5
    Petty Officer 2nd Class Merc4ever's Avatar
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    Default Re: 4.3 Mercruiser Thunderbolt IV base timing

    Once again, Thank you all very much!

  6. #6
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: 4.3 Mercruiser Thunderbolt IV base timing

    My manual covers several years but doesn't specify the Thunderbolt IV doesn't have the wire.
    That is because when the TBolt IV system was used, there was no such thing as TBolt V and putting things into base timing. So why would they specifically say not to put in base timing mode ???????
    Don S.


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  7. #7
    Moderator Bondo's Avatar
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    Default Re: 4.3 Mercruiser Thunderbolt IV base timing

    Quote Originally Posted by Don S View Post
    Quote:
    My manual covers several years but doesn't specify the Thunderbolt IV doesn't have the wire.
    __________________________________________________ ______________________
    That is because when the TBolt IV system was used, there was no such thing as TBolt V and putting things into base timing. So why would they specifically say not to put in base timing mode ???????
    Ayuh,...
    Any Grease is Better,..... Than No Grease at All.......

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