here is something else i found on this forum.
I am an engineer. I am very familiar with the t-bolt IV and V and its functions.
I would lean toward getting the t-bolt V components and switching back. Yes, I know what it cost, but heres my opinion and why.
The t-bolt has a very hot spark. If you remove the spark cable from the center tower and crank the engine, a bright white spark will jump from the center tower to one of the coil terminals. And, that's while the battery is at 8-9 volts while cranking. The plugs in that engine were chosen to work with that spark intensity, and ignite teh fuel throughly. Note: you MUST use the merc coil with the t-bolt series systems. I even tried a MASCAR grade coil and the boat ran badly.
Next, and this is the most important part. The timing is done in the pack, not the distributor. The t-bolt ignition systems have a memorized advance curve.
This was adaquate and produced reasonable power for the RPMs. The t-bolt V has a knock sensor. The system will advance the timing until it knocks and back it off until it stops. So, simply put, the system operates the timing at the best spot for whatever conditions, gas grade, sea conditions, etc will allow. This makes HP better and even results in a slightly better fuel burn. Their specs state as much as 10 degrees, + and -.
My 5.7 has the t-bolt V. Its rated at 250 HP. The same engine and carb with the t-bolt IV was rated at 220-230 HP. SO, you can see the benefits of teh V.
Next, the t-bolt systems were designed time engines for a marine loading. Its wayyy different. Like in a car or truck, you may use 200 HP accelerating to hi-way spped, and use maybe 30 HP to keep it there.
If a boat requires 120 HP to cruise, you are using 120 HP all the time.
Lastly, if the timing is advanced too far, it may burn a hole thu a piston top.
As an engineer, I learned not to second guess someone elses design. They do a lot of testing and have to warranty it for up to 7 years. they certainly don't want to give you another engine for free.....