Thunderbolt IV module on Thunderbolt V ?
 

just did a 454 to 502 swap and have TB V ignition with knock sensor. My rev limiter is too low at 4700-4800 so i want to change it. Can i just unplug the TB V ignition module and plug in the TB IV one? Will the TB IV work with the knock sensor or do i disable that too by unpluging it too?

What is the best Ignition module for my New gen 6 502 415hp carb holley 800, EMI headers with long tubes? IN a heavy baja outlaw24.

Dont want to go MSD, want to keep the super reliable TB ignition!

thanks

Some else might speak up but isn't a TB V controlled by the ECM and knock sensor. TB IV does not have an ECM.

Mine doesnot have a ecm just a Ignition module and the a knock module on top...let me see if i can get a pic..I know that some do have an ECM but i think only on TB V that ate v6 4.3. Mine was a 454 carb 330

THis what I have....very simular to the TB IV...no ecm..

CHECK OUT PAGE 16, AND THEN THE WIRING CHART.
http://www.boatfix.com/merc/Servmanl/16/16B4R2.PDF

You could just get a TB IV module and the plug in harness that goes with it. It will not have any rev limiter. That or get a TB V module from a different, higher reving engine. PM rsteiny, he may have a V off his. You could probably also have the rev limiter raised in your module, but not sure about that.

Griff, did u see what the module that i have looks like? It sort of looks like a TB IV module but its a TB V. its nothing like the HP500 or bulldog 500 TB V module, those look more like an ECM and have two conections on them. I know my module that i have isn't progrmable, the color on the wiring schematic are the same except for the wire that goes to the knock sensor. i just dont want to get into switching my entire harness over, cuz i just got done, extending some things and retapping and wire looming the whole thing before i droped my new motor in last weekend.

Do you think mt stock 502 mag shold rev more than 4700? i think thats where my rev limiter is set at but dont know.

All the info you need can be found at the link below assuming you are talking a 502HO (450HP)

Max RPM = 5500

Max HP is made at about 5200

http://www.gmperformanceparts.com/En...8778&engCat=bb

Yes, I saw the pic. Yours is on page 4B-14 right??? Your module is the same as what was used on TB V carbed 500hp's. Yours is just mounted on the distributor and the 500HP ones were not.
http://www.mercruiserparts.com/Show_...RU+0L001772%29

Ya thats mine, I think i figuared out what to do, i just need to get a 454 Mag module from a thunderbolt V!!! Dont know whay i didnt think of that way back......I however gooled the part number and cant find one unless i buy new and they are 400 plus dollors. Someone i'm hoping has one. I think the mag has the rev limiter at 5250.

806745A01 MODULE-Ignition Control old number 806745T5 (454 MAGNUM)

454mag will have a 5150 rev limit and the 500HP will have a 5350rpms limit. Either will work fine.

Anybody have a timing curve for the Hp 500 carbed ignition module?

What is the RPM limit on the1999 HP500 carbed modules?

From all that I have read, looks like if its a Thunderbolt V Ignition with knock module the rev should be at 5350. And the timing curve is ever changing from what i have seen because its constantly checking for knock and advancing and retarding the ignition fo more power...

Can a 1989 420hp 454 ignition module be used on a 1999 HP500 carbed engine?
Are there any problems switching them or with the knock sensor?

Engine harness is different, and you cant use the knock sensor form your 99, you can use the distribitor from the 99 hp. why would you want to take an old ignition system and run it on a new hp500. Run the Thunderbolt V with knock . Is your module dead on your TBV

I have not checked, but if the Tbolt IV and V pickup sensors are the same, you could use the IV module and toss the knock sensors.

Trying to increase the rev limiter above 5200.

Suggestions?

See i had the same problem, but i ended up ordering a 454 mag TB V module that is 5250 limmiter which will work good for me, but for you you need eilther a TBIV module, you can use your distributor and either hack into your harness or if it was me buy a new harness. Memeber Rockfish was selling a HP500 TB IV harness last week on the swapshop. Your knock module will not work anymore. So just run a TB IV module V8-hp one or one of the others.

Crane's fireball i think its called is super cool, i almost bought that built in ignition curves and rev limiter that you set, very easy, and you could run your old harness you have now, minus the Knock module.

I was just informed the rev limiter is a separate unit inline on the harness from the ignition module to the distributor?

Is this true and can it just be eliminated?


Another question...Does the crane HI-6M still utilize the knock sensor?

I assume this is the Crane ignition system you were talking about.

The rev limiter on a Thunderbolt 4 system has a external rev limitor on your hp500, but thunderbolt 5has it on the module from what i have read. Thunderbolt 4 module dont have rev limiters so merc racing put seperate rev module on, and alot of people just take them off.

Ya the crane system is the one i was looking at. your knock senor module will not work with it. There is an aftermarket one i think you can but for the crane system......its in there directions on there site.

The stock rev limiter should be at 5350rpms whether its a TB IV or V. The IV has an add on rev limiter and there is no rev limiter built into the actual module.
If you have a knock sensor, then you have a TB V.

This a TB IV and part #41 is the rev limiter
http://www.mercruiserparts.com/Show_...CAL+COMPONENTS

I have a knock sensor and it is a Thunderbolt IV. RPM limit seems to be 5200.
Here is my engine specs


http://www.mercruiserparts.com/Show_...RU+0L001772%29


Is the rev limiter part of the knock control? Can it be removed from the wiring harness?