the merc thunderbolt4 is hardly cheep crap as you put it,i agree that with a captive discharge ignition like the msd 6 box the engine will idle cleaner due to the multiple spark,but that stops at 3000 rpm,then it produces 1 spark per firing cycle,same as the thunderbolt4.unless the engine is high compression or supercharged ,the thunderbolt4 will fire the plug just as good as the msd will,also,please explain to me how the ignition system has anything to do with the amount of fuel that enters the cylinder to make more power.

Ok. I will do that tomorrow.

as far as ignition goes, the motor needs what it needs and no more. if the stock ignition was sufficient for the air/ fuel/ compression ratio you have then MORE ignition buys you nothing at all... and for the record , as far as " stock cheap crap " goes, the factory ignitions in most case is a far better engineering and manufacture exercise than the vast majority of the aftermarket junk. in the "cheap crap" catagory MSD is the world leader. if you are going to run that junk i have only two words of advice...

carry spares

Is there a prefered coil to run with the TB4? And what is the difference between a TB4 and a V8-HP module?
Not to hijack the thread but I'm in the same "boat" as Chris the OP.
Thanks.

the best bang for the buck is a H/P version of the old style HEI, I get the vacume advance block off and the 2 wire ends to make the swap a snap...ran several of them, worked great everything less than $100..

Are you talking about old style automotive HEI

+1...great folks to work with....very high quality simple equipment.

My engine builder has told me he has seen as much as a 40hp gain on the dyno with the MSD HVC II coils. My brother in law has done some work with Ford engineering on some special spark plugs that they gained 30hp from. I am of the theory that a larger, hotter, longer spark creates a bigger, faster, flame front and thus more power. When I was a kid and had a 14:1 go cart race engine running 14,000rpm just spark plugs made a huge difference. When it comes to horsepower, everything matters, no detail is to small to overlook. Remember in the words of Smokey Yunick, "It's easier to find 100 ways to make 1hp than it is to find 1 to make 100hp". As far as the factory stuff goes, you have to evaluate their goals verses your goals. Their CFO wields a bigger stick than ours (sometimes). Their goal is to get it done for the least cost, my goal is to get it done for the most gain. Just do a spec check, the current, dwell, and voltage coming out of a really good ignition system is significantly better than anything factory. Factory motors aren't designed around 10:1 compression running at 6,000rpm either. Just my 2 cents.

never said anything about h/p numbers......starts,idles/runs smoother.msd

sorry,it was likefastboats that said he gained 37 hp with the msd ignition,i am still waiting for him to post his back to back dyno sheets.i thought he was speaking for you.