mjw930

I'm looking for technical information on the following TB V ignition module:

806959A01 (old #806959T4)

It's from a 1996 7.4L / B1 package, SN OF810055. I'm looking for the ignition curve and the rev limiter specification.

I'm not looking for generic info, I need to know specifically what's programmed into THAT part number.

Thanks.

Dave_N

There is no published advance curve on any individual T-bolt V module. Due to the "Mean Best Timing" and idle speed control functions the advance curve is variable and therefore can't be plotted as a single line on a graph (unless locked in base timing mode which disables the MBT feature). The graph below is as close as you will get to what you are asking for.

mjw930

Dave,

Thanks, I already have that. What I need to know is what rev limiter they programmed into THAT module. I've seen all kinds of tribal information, some saying it has no limiter to others that say 5100 but I'm seeing about 4650 - 4700 on mine and I want to confirm that.

Merc has multiple versions of the TB V module, all with the same hardware but each with a different firmware load. Even on the '96 specs they have a different part number for 454 Mag vs. 7.4L.

I suppose I could call Mercury but it's unlikely I will find anyone either willing or able to look up the answer.

mjw930

Wow, I called Mercury and actually got an answer!

Operating range 4200 - 4600, Rev limit 4750.

From what he said the rev limit is usually 150 rpm higher than the top WOT rpm number published for the motor. That would explain the 5150 from the Mag modules (WOT 4600 - 5000).

Griff

7.4's have the rev limiter at 4700 +/-
454/502 mags have the rev limiter at 5100 +/-
500's/525's have the rev limiter at 5300 +/-