So this year my 406sbc is going to have 480-500 hp this year and Im thinking that I have too upgrade from my Thunderbolt 4. Can you guys recommend what to buy? or point me in the right direction... Im not looking for the best of the best... money is a little tight after upgrading heads pistons etc... I didnt think about this at the time of buying everything else.

Unless you are having problems fouling plugs easily at idle, then the TB 4 should still work fine. You will probably want to use a V6 or V8-HP module though for a faster timing curve.

I use the Davis Unified Ignition distributor/coil they tune it for your motor/ boat. I have not had a lick of trouble out of them...

When we had my motors on the dyno we started with the Thunderbolt ignition and did a couple of pulls and got 661 HP. Then we installed MSD Pro Billet Distributors with their Marine Ignition Boxes and run a few more pulls. We got 698 HP. Thats 37 HP with the only change being the Ignition. We did the same thing with both motors so it's not a fluke. I was totaly impressed.

if you had gotten the timing correct with the TB4 you would have made the same power. there is nothing magic in the MSD.

and please... no nonsense about how the MSD made power... it " made" nothing at all. if your original ignition was garbage and you had replaced it with stock, you would have had the same power.

I will say this about msd.the motors start,ldle,and run better.part are cheap...and yea.u get what you pay for.but they fit my bugget and i have/carry spares

bcfountain,unless you are burning methanol alcohol or nitro,you did not gain 37 hp by switching to msd ignition,if everything else was the same,the thunderbolt4 will make the same hp as the msd will.

Well all I know is what the dyno numbers were. We changed absolutly nothing but the ignition. Exact same timing, jetting, ambient air temp, humidity, water temp., etc. ect. And as bcFountain said they start better, idle smooth, no stalling and just basicly run better than they did with the stock ignition. And the 37 HP came from somewhere, both motors same exact results, if it wasn't due to the ignition where did the extra ponies come from??

Sorry for the multiple posts but what you guys are saying is really baffling me. With a hotter more controlled spark you will get a more complete burn of the fuel. More fuel burned, more horsies. Why would racers or any body for that matter spend money on high doller ignitions if cheap crap stock ones work just as good???? If what all you are saying is true MSD, Accel, Pertronix and all the others would be out of business.

post the dyno sheets!