1997 Mercruiser 5.7 Alpha, was a 2bbl, non vortec heads. Standard ignition system. The new engine has Vortec heads, Howards Cams Roller cam, Edelbrock RPM Air Gap intake. Standard exhaust manifolds. The cam manufacturer said I want between 32-34 degrees of timing at 2500rpm. Going by the book, and the cover on my engine, it looks like base timing is 8 degrees btdc, and 22 degrees module advance, for a total of 30 degrees. Can I swap modules from a different engine to get to the 32-34 degree range? Anyone know of a particular engine that has that? Thank you in advance.

If you have Tbolt IV ignition, just set total degrees where you want it...and let base fall where it falls.

Do you have Tbolt IV or V ? What module # do you have ?

I am not sure of my part number. Looks like I have Thunderbolt V, and I believe it says v8-22 on the module

Tbolt V uses a mean best timing set up...using a knock sensor and tachometer......so very unconventional. It also has a special procedure to check base timing because of all of this. Do a search on it in google land to learn more...I'd have to write a small book to let you know all it's workings.

Tbolt IV is conventional...ie: doesn't adust for anuthing...just has an electronic advance.

I know mine does not have a knock sensor. I have timed it before and there was a sequence of grounding a wire to set base timing if I remember correctly. Is it hard to switch to thunderbolt iv? Would my distributor be ok, and just change module/sensor in the distributor? Thank you for the help.

I could be wrong, but I have not seen a Tbolt V without a knock sensor.

Here, go nuts:
http://www.boatfix.com/merc/Servmanl/16/16B4R2.PDF


Edit in: oh, you would have to swap the module harness to go from a V to a IV.

Found a module from a thunderbolt IV that is V8-24. Anyone know if the wiring is the same?

Look up , we posted at same time...lol.

From what I have read, Vortec heads do not like more than about 30* of timing.

I would characterize it as not that they don't like more than 30* of timing but rather they don't respond as much to timing over that amount. I would still target 32*.