Only a certain amount of voltage is needed to jump the plug gap. Anything more than that is wasted money. My motor made 600hp with the stock coil. The only that it will replaced is when it fails.

I'm not trying to rock the boat,
 

but let me share my experiences with you guys. I too always thought that the stock merc TB module and coil were plenty. I damn well liked the electronic curve rather than going with mechanical (stone age?) advance mechanism. If you want to add a different coil - big deal. It wasn't until this motor that I became sold on the CD ignition (I'm sure other brands are great as well as MSD). I had 2 NA motors with Merc HP modules (straight 20 degree advance) with great performance. Had a blower motor with V6 module that seemed to run fine, if you had clean plugs. My current motor ( a blown 540 running more boost) however just didn't run right and constantly fouled plugs (even at 2500 rpm!). I was really questioning the fresh Nickerson carbs. Several people asked if I had an MSD (or equiv) ignition amplifier (teague and others). I kept thinking that money would be wasted. Finally got fed up and put it on the dyno and saw 30 ft-lbs more torque from the MSD alone (with the fouled plugs). During several pulls where we adjusted timing and valves, the once fouled plugs started to clear up. When I re-installed the engine in the boat and put a set of fresh plugs in, they have stayed clean every since, to me, proving that the carburation was not off, but the mixture was not getting ignited completely.

Maybe this is not as true for NA engines, but take it for what it is worth as far as someones elses experience goes. I really think that it has a lot to do with effective compression ratio. So take the example of a 600hp 540 that has 9:1 compression compared to a blown 8.5:1 (static) 454 with an effective 11:1 ratio. I think that the higher combustion pressures require more spark energy to get proper ignition in the blower case ( and don't hurt in the other case. You can still use the TB module to get your advance curve, using the MSD box as an ignition amplifier.

Good Luck!

A ballast resistors only purpose in life is to prevent points from getting burnt during long periods of idling. Hence no points.. no ballast resistor necessary.

BT :cool:

Brad-I agree. I think that every serious blown motor and motors with dominator carbs should have a cd system.

TGary... what improvements do you think Ill see using the new module? Thnx sj

So anyway, whats the part number?

It will also idle lower and smoother with the MSD ignition system.

What you can do is just install the MSD box downstream of the stock ignition module and then you will get the best of both worlds.

TG... any luck with that info?

Stevejohns, I will try to rember to get that part # today. You should definetly notice better throttle response. I"ve never done it myself, as I no longer have ascess to a dyno, but I've talked to people who have done back to back test on both ignitions. According to them the difference is minable. One reason people go with MSD, is they are cheaper than Merc Hei. We have replaced more MSD boxs than Merc amps. Why do you think Nascar runs a back-up MSD. Why do you think they run them at all? Because MSD is a corporate sponsor.

Stevejohns, the part # is 15247A1