Dual Ignitron System Thunderbolt IV & MSD6 AL confirmation run on schematic

[monette999]

Dear All,

​I would like to implement a Dual Ignitron System Thunderbolt IV & MSD6 AL on my boat. In case my OE System fails I have a backupsystem on
board. For the ignition advance I have purchased a extra Thunderbolt Ignnition amplifier.

I will have one OEM distributor and one cut out swich. Who can work on my wiring schematic attached & let me know if my wiring is OK.
I want to use a toggle switch & shut off the OEM system.
Is the +12 igntion on the coil is supplying other componments on the engine.

Sometimes the real wiring is different to the schematic.

I think I need to supply the Hall Switch from the distributor with separate +12V, otherwise I have no trigger signal when I switch to MSD system.
correct?

Here a draft of my schematic diagram.

Now why I am doing this ? I would like to have a direct comparison if an MSD will perform better as the 20 year old design of mercruiser.

My point are related to hot start and performance.

BR
Bob

 

[Scott Danforth]

why over-complicate the ignition system? when ever you add "redundancy" you actually exponentially increase the probability of failure. the TB IV system is fantastically reliable and the MSD wont perform any better.

 

[Scott Danforth]

not to mention that the MSD 6AL is not SAE J1711 compliant, so you create an ignition source for a large BOOM. the red MSD boxes are not sealed, so in a marine environment that becomes a reliability point from corrosion as well.

 

[alldodge]

This question comes up ever so often, as yet no one has come back that I can remember of getting it to work. That said I also suffer from CRS

I don't see it working because the trigger signals are connected to both boxes but only one is powered. The signal is small and there can be an issue with loosing part of it during operation. Is that enough to cause its own issue I don't know.

I would think it could be done but not with a switch, but a plug. If two modules can be installed in one distributor that would be the first part, and add another coil. Now bring all power and signal wires of the TB-IV to one location and connect to a male/female plugs. Now run all wires from second system components to a matting connector. If the system fails, unplug first system and plug in the second, move coil wire and fire it up.

If you do manage to get it work please let us know. I promise to try hard to remember for the next guy.

Edit: and agree with Scott's non-marine point

 

[monette999]

Hi All-Dodge & Scott

Scott is correct with the MSD, but I can buy a marine compliant MSD. That is solved now.

Now let talk throught the technical points.

Trigger has to supply two systems.

I assume that the Thunderbold trigger circiut has an MOS-FET transistor inside. They have a high impeadance and I am not worried about my trigger signal.
Shall be okay.

The hall trigger signal (Distributor) is getting 12V from the Thunderbold IV module 1. When I activate the toogle switch I am switching the 12V between module 1 to module 2.

Both system are connected to the hall switch. (paraelle) Am I wrong, see green & red dotted line. The hall cell shoud be always supplier with 12V.

By the way what means CRS?

AllDodge, why do you think the switch is not working ?

 

[alldodge]

By the way what means CRS?

Can't remember stuff (there is another word normally used

AllDodge, why do you think the switch is not working ?

Mainly because there have been many which have tried to do it and no one has ever come back saying it works. All have started the same way your doing, but again nothing on the net that it worked. There are other threads on other forums which I am a part of and nothing back from them either.

 

[Scott Danforth]

First rule in reliability.... Keep it simple. Either go with the MSD marine box ( actually a big waste of money for small displacement non-blown motors), or run the factory ignition system. There is no one I know that has ever successfully done what you are attempting.

 

[achris]

It looks like all you're doing is trying to put in place a 'switch over' to another module if the original fails. You still have multiple points of failure outside the module. But that aside, if that's what you are trying to do, why not make it much easier. You say you have a second TB-IV module. Why not mount that near the original, and then just move the plug across in the event of a failure? Alternatively, get another engine harness and use just the module connector and put a 4 way toggle switch in.

But, I'm in the K.I.S.S. crowd...

Chris......

 

[monette999]

Chris I want to have a full redundant system.

I have used my scope and was monitoring the Trigger voltage. White / Green cable :3.9v.
You are pulling the 3.9V to Gnd the system Sparks.
I will splice this Signal. Let's see what happens?

keep you in the loop.

 

[achris]

As a comparision system on the same engine, side by side, it's almost worth it.... As a backup system for failure redundancy, it's not 'value for money'....

Good luck, and I look forward to the results.

Chris.....