Speed H2O

I have a thunder bolt V ignition on a carburated HP500,
I have heard that swapping to a V-6 mercury ignition module
will be better due to the timming curve if adding a blower.
..anyone know if a thunderbolt IV module for a V-6 with 14 deg. advance( p/n 805361T1) will work on this engine that currently has a thunderbolt V module?
Thank's,
Mike

BadDog

Mike,

I don't know anything about blowers other than what I have read here. You are on the right track and someone with firsthand knowledge can confirm for you. You may want to investigate the Crane Hi6M ignition system. You can rotate a dial or so and set most any ignition curve you want as well as switch selectable retard (in case you have a load of lower octane fuel) and it has a hookup for a knock sensor. Check the classifieds.

http://64.90.9.168/cranecams/pdf/90006462a.pdf

Tim T.

Smitty

I had the same question so here is the answer. You need Merc ign module #848823-2.

This is the factory module used on a 525SC motor. What you get is a 5300 rpm redline versus 5050, A total advance of 30 degrees and it brings total advance in a little sooner. Works great on my Whipplecharged 454 Mag.

Dave

Speed H2O

Dave,
thanks but my rev limeter is 5350 right now stock......??

BadDog

The Crane has an adjustable rev limit as well.

Brad Perry

Don't take it wrong, but I don't think he wants that module (525). That motor runs a lot more total timing with a 7.5:1 compression than most blower motors. I'm guessing that you are looking at 28-32 degrees max timing and the merc v-6 module will work great for that. You will get plenty of initial timing and no rev limiter. It will wire in fine with that TBV motor. Down side that I see, is that it start's it's curve very early. and this adds to a root's surge in the idle. I don't think it's adequate above 600hp or so. Blowing an hp500 is probably going to put you above 600hp, so might as well go with the crane or msd.. I just went with locked out timing and an msd 6al and it works great. Sounds like the crane has more features though.

Speed H2O

Brad, you are correct....525 module has too much total advance.
Thank's for the info!

bobby daniels

ALSO MSD HAS BEEN AROUND ALOT LONGER THAN CRANE AND IS A MUCH TOUGHER PART ,YES I KNOW HUNDREDS WILL COME ON AND SAY CRANE IS ON THEIR BOAT WITH NO TROUBLE ,I KNOW THIS BUT MSD HAD BEEN AROUND SINCE THE 70'S AND HAVE BEEN USED ON WINSTON CUP ,NHRA SINCE THEN ,IF YOU MEASURE THE SPARK THE SAME WAY BOTH UNITS ARE ABOUT THE SAME IN OUTPUT !!! THE NEW DIGITIAL BOXES ARE KILLER
YOU DON'THAVE TO RUN THE MARINE BOXES AS ALL MSD'S ARE EPOXY FILLED NOW NOT LIKE THE OLDER ONES ,,,JUST MY 2 CENTS WORTH

BOSSMAN

I have 500hp with blowers with inner coolers. I tried v6 boxes but like perry said you will have over 600hp and I found out the only way to go was with the msd boxes with the retard control.I run a 40 ft boat at 5000 rpm 8lb boost runs 93 gps. The timing starts at 36 degree as rpm goes up timing falls off so at 5000 rpm I only have 28 degree. Do not have a problem of blown engines like I had with v6 boxes and I know if I really want I could go faster by running at 30 or push my luck at 34 degree. I can run all day hard and never have hi oil temps or hi water temps.

RLW

Bossman,
What kind of setup do you have? I have the MSD 6BTM ignition. I do not use the Boost Retard feature. My timing is locked in at 29 degrees.
I am running a blower with a Superchiller.
You are running 36 degrees at idle?
At what rpm are you starting to make boost?
Correct me if I'm wrong but do you have the Boost Retard set to retard the timing 1.5 degrees for every pound of boost?
Thanks, Russ