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Thunderbolt V vs 350 Mag Stern Drive Ignition Module?

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  • Thunderbolt V vs 350 Mag Stern Drive Ignition Module?

    I Purchased boat a couple years back and have taken too long to restore it. Way too long... But, all is almost complete. Former owner indicated MC V8s had Thunderbolt V ignition systems with knock sensors. While motors were on stands, I noticed that "350 Mag Stern Drive" labels were on both distributor modules, including knock sensors. However, my manual indicates that these modules are for EFIs. My motors both have 4 barrel carbs. During sea trial, these worked great. I suspect former owner mixed and match available parts which would work OK, or should I have an ignition module specifically labeled "Thunderbolt V?" Not familiar with this specific module...

  • #2
    The TBV should have a number listing how many degrees advance it provides (22 or 24). The TBV will work the same for an EFI or carb motor. Does the module have a part number listed?
    94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
    95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
    07 Seadoo GTX
    Merc Adults Only VP Adults Only
    G-Dad always said "First Liar doesn't stand a chance"

    Comment


    • #3
      Originally posted by AllDodge View Post
      The TBV should have a number listing how many degrees advance it provides (22 or 24). The TBV will work the same for an EFI or carb motor. Does the module have a part number listed?
      Yeah, but I am not able to access right now. As soon as I get back from other duties, I will supply. I would have thought "Thunderbolt V" would have been labeled somewhere on distributor or module. Only the "Mag 350..." THX

      Comment


      • #4
        Distributor for TB 4 or 5 are the same, only the module are different. The modules do look different

        https://forums.iboats.com/forum/engi...n-systems-work
        94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
        95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
        07 Seadoo GTX
        Merc Adults Only VP Adults Only
        G-Dad always said "First Liar doesn't stand a chance"

        Comment


        • #5
          Originally posted by AllDodge View Post
          Distributor for TB 4 or 5 are the same, only the module are different. The modules do look different

          https://forums.iboats.com/forum/engi...n-systems-work
          Good to hear AD, ... I think. My '96 4.3 has a TB4 and I pucker when I consider what to do if/when it fails. Since TB4s are NLA will a TBV work if I need?
          '96 Larson 174 SEI BR. 4.3LX 4 bbl Weber s/n 0F786604. Alpha One Gen II s/n 0F709315

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          • #6
            Yes, TB4 to TB5 will work, just need a couple more wires. Most when a TB takes a puke they replace with Delco EST
            94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
            95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
            07 Seadoo GTX
            Merc Adults Only VP Adults Only
            G-Dad always said "First Liar doesn't stand a chance"

            Comment


            • #7
              Originally posted by AllDodge View Post
              The TBV should have a number listing how many degrees advance it provides (22 or 24). The TBV will work the same for an EFI or carb motor. Does the module have a part number listed?
              Attached is photo. Only number that is easily seen is 806957-2 that is on both modules on both distributors/motors.

              Comment


              • #8
                That is for the 5.7 as shown and new number is 807264T4 and should be 24 degrees total advance. Carbs where set at 10 and EFI set at 8 BTDC
                94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                07 Seadoo GTX
                Merc Adults Only VP Adults Only
                G-Dad always said "First Liar doesn't stand a chance"

                Comment


                • #9
                  That is a Thunderbolt V module for a 350MAG engine, with knock sensor. Have you read my article on the Thunderbolt ignition system? (Here it is if you haven't -> http://forums.iboats.com/forum/engin...n-systems-work) That should clear you any misunderstandings you have of the system.

                  Chris......
                  xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
                  The world takes on a whole new perspective when viewed from 100’ below.
                  1972 Bertram ‘Bahia Mar’ 20
                  2006 Mercruiser 4.3MPI (0W617679) w/Alpha One Gen II (0W829301)
                  (Original - 1972 '165' In-line 6. Previous - 1994 4.3LX)


                  Comment


                  • #10
                    Originally posted by AllDodge View Post
                    That is for the 5.7 as shown and new number is 807264T4 and should be 24 degrees total advance. Carbs where set at 10 and EFI set at 8 BTDC
                    It will advance 24 degree total or 24 more degrees or 34 degrees(10 +24)? So I disconnect knock sensor and set timing at 10 degrees advance instead of 8 degrees advanced? Hum....I would have thought the opposite for carbed motors. I would have also thought MC would have had TB v or similar on label or maybe former owner didn't have access to these modules and used what he had access to. THX!

                    Comment


                    • #11
                      Originally posted by achris View Post
                      That is a Thunderbolt V module for a 350MAG engine, with knock sensor. Have you read my article on the Thunderbolt ignition system? (Here it is if you haven't -> http://forums.iboats.com/forum/engin...n-systems-work) That should clear you any misunderstandings you have of the system.

                      Chris......
                      I will! Thx!

                      Comment


                      • #12
                        Originally posted by achris View Post
                        That is a Thunderbolt V module for a 350MAG engine, with knock sensor. Have you read my article on the Thunderbolt ignition system? (Here it is if you haven't -> http://forums.iboats.com/forum/engin...n-systems-work) That should clear you any misunderstandings you have of the system.

                        Chris......
                        Excellent information but I didn't see anything on "350 mag..." So, the "350 mag..." actually referred to motor and by default was a TBV ignition system? THX

                        Comment


                        • #13
                          Ok. Thunderbolt is the trade name for Mercury's ignition systems. The 'original' Thunderbolt was on the inline outboards. In 1984 Merc put Thunderbolt (series) IV on the Chevy block stern drives and inboards, then in 1996, released (and fitted) Thunderbolt V series. Each TB module (be it IV or V) has the timing curve of the designated engine programed in.

                          The designations for TB-IV was the engine and the maximum advance (of the module), sort of. These were all the TB-IV modules fitted to the Mercruiser engines. That's between 1984 and 1996.
                          V6-14
                          V8-20
                          V8-20R
                          V8-22
                          V8-22A
                          V8-24
                          V8-24S

                          Which module went on which engine (and the actual timing curve) can be found in service bulletin 95-11 (easy to find online)

                          The TB-IV module for a 350MAG was the V8-24S, which also went into a whole bunch of other engines, that's why there isn't engine designations on the TB-IV modules, just one of the codes above.

                          In 1996 with the advent of TB-V and an adaptive curve, these codes no longer applied, so either part numbers or actual engine designations started to be used.

                          That's why on your module there is a part number and the engine designation. No, there's no "Thunderbolt V" written on it, that's implied by the module itself. It's a 'Thunderbolt V' module....

                          Hope that helps...

                          Chris........
                          xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
                          The world takes on a whole new perspective when viewed from 100’ below.
                          1972 Bertram ‘Bahia Mar’ 20
                          2006 Mercruiser 4.3MPI (0W617679) w/Alpha One Gen II (0W829301)
                          (Original - 1972 '165' In-line 6. Previous - 1994 4.3LX)


                          Comment


                          • #14
                            Sign up today
                            Originally posted by achris View Post
                            Ok. Thunderbolt is the trade name for Mercury's ignition systems. The 'original' Thunderbolt was on the inline outboards. In 1984 Merc put Thunderbolt (series) IV on the Chevy block stern drives and inboards, then in 1996, released (and fitted) Thunderbolt V series. Each TB module (be it IV or V) has the timing curve of the designated engine programed in.

                            The designations for TB-IV was the engine and the maximum advance (of the module), sort of. These were all the TB-IV modules fitted to the Mercruiser engines. That's between 1984 and 1996.
                            V6-14
                            V8-20
                            V8-20R
                            V8-22
                            V8-22A
                            V8-24
                            V8-24S

                            Which module went on which engine (and the actual timing curve) can be found in service bulletin 95-11 (easy to find online)

                            The TB-IV module for a 350MAG was the V8-24S, which also went into a whole bunch of other engines, that's why there isn't engine designations on the TB-IV modules, just one of the codes above.

                            In 1996 with the advent of TB-V and an adaptive curve, these codes no longer applied, so either part numbers or actual engine designations started to be used.

                            That's why on your module there is a part number and the engine designation. No, there's no "Thunderbolt V" written on it, that's implied by the module itself. It's a 'Thunderbolt V' module....

                            Hope that helps...

                            Chris........
                            Very much! Thanks!!!!

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