Late 80's merc 420's, upgraded to 550 hp, for a couple seasons, and now adding 8-71's w 5psi.

At what RPM does the Thunderbolt IV start advancing?

We have MSD boxes but this may be an easier more reliable route.

Thanks

There are different curves depending on which module you run. Many people (myself included) run the V-6 module which only advances it about 10* and I believe it's all in by about 2500.... Post which modules you have and I'm sure someone can oust the curves. Or you can just google them

Pm me your email address. I can send you pdf documents all about tb1v ignitions.
Might take me a day or two to reply, they are on my laptop not here.

Sweet! Thanks for the inputs!!

Here: http://www.offshoreonly.com/forums/g...-ignition.html

and here: http://www.boatfix.com/merc/Techbk/95/95HGB4.PDF

There's a thread on here about the TB IV modules and advances, I'll see if I can find it.

Post #4 on my first link. Click on photofor bigger version.

And from Merc themselves, and most common modules, a few pages in to my 2nd link above.

Does anybody have the differant curves on a V6 moduals on a V8 motor?

I ran the V6-14 module on my old Top Gun, 750 blower motors. When the V6 module is fitted to a V8, it only advances about 8 degrees, If I remember correctly the V6 module starts advancing at 650 rpm. so if you're idle is set around 1000, a fair amount of advance is already out. They work pretty good for an application like these.

^^^^^^^ That is correct as the V 6 - 14 module matched to a V-8 will advance to 6 to 10 degrees. Average is around 8 degrees ^^^^^^^^