I am looking for a pair of Mercruiser Thunderbolt IV Ignition Advance Modules. Specifically the V8-24 modules, the old part number was 15248A1 and the replacement number is 15248T01. They are embossed (heat stamped) with V8-24 near the connector end. If you have a lead on some, please PM me. Not needing new, would prefer used, I am running some test and was wanting to try before buy.

Send a PM to Sick Stinger. I would bet he has some.

The V6 module has 2 degrees more advance. You can use those, but just make sure you account for the diff.

Huh????

A V8-24 has 24* of timing advance and is at full advance around 3500rpms.
A V6-14 has 14* of timing advance on a V6 engine and only about 10* of advance on a V8 engine and is at full advance around 1800rpms on a V8 engine.

This may help.

Alternative facts Gary. I know you’re trying to peddle your stash of diesel ignition modules. Busted!

LOL, That's the chart I posted on OSO about 15 years ago. Its from Dennis Moore's BBC Marine book.
And the first V8-22 column is actually a V8-22A that came on the 525SC's.

Yea but mine are wireless.

Sorry Griff. I have no excuse for it, and have never substituted a V6 module but worked with a guy who swore they were the hot ticket and I never paused to do the math in my head to see how backwards his idea was. I vomited out bad info. Thanks for calling me on it.
Every Tbolt 4 motor I've played with I just set them at 36 degrees at whatever rpm they stop climbing and forget about them. I do like to use a piston stop and timing tape to make sure the TDC mark is accurate, especially on motors over 10 yrs old and anything that has been backfiring.

No need to be sorry I know you give out a lot of really good detailed info on a lot of topics.

The V6 modules do work well in some cases, especially on big cam engines with idle issues and on some blower engines.
They are pretty much one step away from running the timing locked.
IMO, the V8-HP modules have the best timing curve for most performance apps, but they are getting hard to find.