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  1. #1
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    Default timing 4.3 with thunderbolt ignition

    I had to change intake manifolds and now i have to check the timing. Can I simply check the timing at idle or are there different procedures with this ignition. Thanks

  2. #2
    Chief Petty Officer mpdive's Avatar
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    Default Re: timing 4.3 with thunderbolt ignition

    Quote Originally Posted by tcline11 View Post
    I had to change intake manifolds and now i have to check the timing. Can I simply check the timing at idle or are there different procedures with this ignition. Thanks
    If it's the thunderbolt 4 ignition, you have to bypass the computer advance by grounding the purple wire lead at the distributor. Set timing and don't forget to take the grounding wire off.
    Sometimes it's more important to be human, than to have good taste. ~Brecht

  3. #3
    Moderator Bondo's Avatar
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    Default Re: timing 4.3 with thunderbolt ignition

    Quote Originally Posted by mpdive View Post
    If it's the thunderbolt 4 ignition, you have to bypass the computer advance by grounding the purple wire lead at the distributor. Set timing and don't forget to take the grounding wire off.
    Ayuh,... With T-Bolt IV, ya just hook up the timing light, 'n shoot....

    T-Bolt V needs the jumper wire to set it to base mode, then time it...
    Any Grease is Better,..... Than No Grease at All.......

  4. #4
    Chief Petty Officer mpdive's Avatar
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    Default Re: timing 4.3 with thunderbolt ignition

    I stand corrected. It,s the ignition amplifier that supplies advance on the 4. The 5 is grounded for base timing. I was confused for a second ,Thanks Bond-o
    Sometimes it's more important to be human, than to have good taste. ~Brecht

  5. #5
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    Default Re: timing 4.3 with thunderbolt ignition

    Thanks for the quick response. I have the TB 5 ignition but it doesn,t have a purple wire on the distributor it ha s a black going to ground and 1 white with red stripe and 1 white with green stripe The only purple wire is from the coil. what do i jump and how.

    Thanks again

  6. #6
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: timing 4.3 with thunderbolt ignition

    It's not on the distributor, look up next to the carb on the starboard side. Why is it newbies never seem to think that a simple think like the year has any impact on their engine? All 4.3's are not created equal.

    time.jpg
    Don S.


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  7. #7
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    Default Re: timing 4.3 with thunderbolt ignition

    I dont have this ignition, mine is IV, but... Manual says for V there is a purple and white wire in the harness, with a spade conector, between the ICM and KCM. Run to engine ground with jumper and this makes it run on base timing. Start and use timing light as usual.

    Note: it also states that the carb shoud be adjusted with the engine runing on base like this as well.

  8. #8
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    Default Re: timing 4.3 with thunderbolt ignition

    Quote Originally Posted by joewithaboat View Post
    I dont have this ignition, mine is IV, but... Manual says for V there is a purple and white wire in the harness, with a spade conector, between the ICM and KCM. Run to engine ground with jumper and this makes it run on base timing. Start and use timing light as usual.

    Note: it also states that the carb shoud be adjusted with the engine runing on base like this as well.
    Thanks for the info I will try that in the morning

  9. #9
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    Default Re: timing 4.3 with thunderbolt ignition

    Quote Originally Posted by Don S View Post
    It's not on the distributor, look up next to the carb on the starboard side. Why is it newbies never seem to think that a simple think like the year has any impact on their engine? All 4.3's are not created equal.

    time.jpg
    thanks for the info. sorry for being a newbie

  10. #10
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    Default Re: timing 4.3 with thunderbolt ignition

    When I checked the timing when I grounded the purple and white wire and set it at 10 deg as it says to on the top of the carb. when I unhooked the wire and checked the timing again it was still at 10 deg. Is this correct or should it have changed. Also it idles just fine but when it gets to about 1900 rpm it starts to run bad and backfires sometimes. What else could be wrong and what should I check next. I also checked the pos side of the coil with the key on and it has the same voltage as the battery. Thanks

  11. #11
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: timing 4.3 with thunderbolt ignition

    Did you set it into timing mode and take it out of timing mode at the right time?
    Did you read and follow the procedure I posted earlier?
    Don S.


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  12. #12
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    Default Re: timing 4.3 with thunderbolt ignition

    Quote Originally Posted by Don S View Post
    Did you set it into timing mode and take it out of timing mode at the right time?
    Did you read and follow the procedure I posted earlier?
    I read the instructions and the only thing i couldn't figure out is where it says to remove jumper wire from timing terminal. Is that the same as the purple and white wire for the ground if it's not the instructions never say hook up any jumper wire from the timing terminal. If it's a seperate step to do can you please explain. The engine is a 2003. Thanks

  13. #13
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: timing 4.3 with thunderbolt ignition

    Read item 8, especially the bold part that says important.
    Don S.


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  14. #14
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    Default Re: timing 4.3 with thunderbolt ignition

    Quote Originally Posted by Don S View Post
    Read item 8, especially the bold part that says important.
    I read #8. I'm talking about #7

  15. #15
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    Default Re: timing 4.3 with thunderbolt ignition

    Step 8 seems to restate what the second part of step 7 says. And then again puts it in Bold
    Does the timing move as rpm comes up?
    Why was this torn apart to begin with?

  16. #16
    Moderator achris's Avatar
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    Default Re: timing 4.3 with thunderbolt ignition

    Quote Originally Posted by tcline11 View Post
    I read the instructions and the only thing i couldn't figure out is where it says to remove jumper wire from timing terminal. Is that the same as the purple and white wire for the ground if it's not the instructions never say hook up any jumper wire from the timing terminal. If it's a seperate step to do can you please explain. The engine is a 2003. Thanks
    Are literacy rates falling that fast???

    Read Item 3...

    Jumper wire = short length of wire used to connect one wire to another or to a ground.
    Timing lead = Purple/white wire that will put the system into 'Base timing mode' if connected to ground when power is applied to the system.

    Always connect or disconnect the timing wire to ground with the ignition key OFF.

    Look, it's easy.
    1. Engine off. Connect purple/white lead to ground.
    2. Start engine and make adjustments where required.
    3. Stop engine. Remove purple/white from ground.
    4. Have a beer... or 3.

  17. #17
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    Default Re: timing 4.3 with thunderbolt ignition

    Easy for you Chris you already know how to do it
    That particular set of instuctions is poorly written, 7 and 8 restating the same thing differently make it sound as if there are 2 wires. Am i missing something ?
    Maybe i need more beers.

  18. #18
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: timing 4.3 with thunderbolt ignition

    Quote Originally Posted by achris View Post
    Always connect or disconnect the timing wire to ground with the ignition key OFF.

    Look, it's easy.
    1. Engine off. Connect purple/white lead to ground.
    2. Start engine and make adjustments where required.
    3. Stop engine. Remove purple/white from ground.
    4. Have a beer... or 3.
    Uhhhhh Chris, you might want to read the manual again.
    1. hook up purple/white to ground
    2. Start engine.
    3. Set timing
    4. Remove purple/white from ground.
    5. Shut off engine.


    Don S.


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  19. #19
    Moderator achris's Avatar
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    Default Re: timing 4.3 with thunderbolt ignition

    Quote Originally Posted by Don S View Post
    Uhhhhh Chris, you might want to read the manual again.
    1. hook up purple/white to ground
    2. Start engine.
    3. Set timing
    4. Remove purple/white from ground.
    5. Shut off engine.
    Ok.. so I shut the engine down before removing the grounded wire... I seriously doubt that will make any difference. The important thing is to ground the wire BEFORE starting the engine and time it while in base mode....

    My bad....

  20. #20
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: timing 4.3 with thunderbolt ignition

    This thread seems to be more about miss-reading and miss-typing than it is about timing.

    Sorry about that Chris.
    Don S.


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  21. #21
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    Default Re: timing 4.3 with thunderbolt ignition

    Quote Originally Posted by achris View Post
    Are literacy rates falling that fast???

    Read Item 3...

    Jumper wire = short length of wire used to connect one wire to another or to a ground.
    Timing lead = Purple/white wire that will put the system into 'Base timing mode' if connected to ground when power is applied to the system.

    Always connect or disconnect the timing wire to ground with the ignition key OFF.

    Look, it's easy.
    1. Engine off. Connect purple/white lead to ground.
    2. Start engine and make adjustments where required.
    3. Stop engine. Remove purple/white from ground.
    4. Have a beer... or 3.
    I did everything exactly as the instructions said. I sure the timing is correct now at 10 deg at 650 rpm as the engine manual says. When I unhook the jumper wire the timing advances like it should. When the engine is at around 1800 it shows about 16 deg. of timing. Now when I tried to go out it idles great and when I give it throttle it only gets to about 2000 rpm and starts to run bad and backfires every once in a while. What can I check next.

  22. #22
    Moderator achris's Avatar
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    Default Re: timing 4.3 with thunderbolt ignition

    Carby or EFI? First of all let's establish what you are working on. Let's start with year, model and serial number.... At the moment we are all just guessing in the dark here....

  23. #23
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    Default Re: timing 4.3 with thunderbolt ignition

    Quote Originally Posted by achris View Post
    Carby or EFI? First of all let's establish what you are working on. Let's start with year, model and serial number.... At the moment we are all just guessing in the dark here....
    It's a 2003 mercruiser 4.3 carburated with thunderbolt 5 ignition. Serial #m625922

  24. #24
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    Default Re: timing 4.3 with thunderbolt ignition

    [QUOTE=tcline11;3506237]It's a 2003 mercruiser 4.3 carburated with thunderbolt 5 ignition. Serial #m625922

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