Thanks for all the input. Dave - I have the V8-20R module. it sounds like I need to install a V8-24 module and set final timing at 32-34. Vmax - I have a more current ignition and I believe I need the module # 15248A1 which is the plastic module design that is riveted to an aluminum plate and mounted on the exhaust elbow. In any case it also sounds like I need to have all my advance in at a lower rpm and only a module chamge will do that

The problem with changing props is that the 24 spinelli that I have on the boat is perfect for getting out of the hole and midrange cruising but it is a little shy of peak rpm.

Dennis Moore's Marine Hi-Perf BBC book lists all Merc's modules and the advance that they are intended to give through the entire RPM advance range. A 24 deg. mod. was standard equipment on all the basic and mid performance packages. I like the V8-20 (not R) for my purposes but my cam is far from stock and I need the extra advance at idle. Sounds like the 24 should really be all right for you when you get the final advance up to that 32-34 deg. range at WOT. (or anything over 3500 RPM with a 24 deg. mod.) Too bad Mike Spinelli isn't doing props anymore cause I know he would have been happy to tweak yours to give you just what you want. He "readjusted" mine 3 times at no charge. But you might give Darrin at Houston Prop a call. I bet he'd fix you up reasonable. TIP: Tweak your engine before you tweak the prop! --- Jer

Power guy the module I have is just as you described 15248A1 which is mounted to a plate for the exhaust elbow. see this web page for illustration and new part cost $260. //www.stemtostern.com/mercindex/GetDiagram.asp?FunctionGroupID=4688
I would be willing to let it go for half that with no shipping charge guaranteed to fill your need. Let me know. If you can find it cheper used let me know and we can negotiate.

VMax-
Give me a call at 802-233-0585.
Thanks,
Dave