1973 Bertram 46 convertible

What model are the Twin Disc gears you already have? Down angle gears are pretty common, Twin Disc makes many. My ZF gears are 10 degree down angle, just like my original Detroit badged Twin Disc gears.

Those gears are out there in several versions of down angle. 7 and 14 degree come up with a simple search. What is the angle with your original gears? What about gear ratio? Are you staying the same as original?

Sounds like you are anxious to get started which is good. I encourage you to do all your homework and have a solid plan before you go too far. Are you retaining existing shafts and props? How about gear ratio? What is the safety factor of those shafts with the new engines if keeping them? Where is the raw water intake on the hull vs. the engines? Are you using existing controls? Are starters and alternators same voltage as existing? Anyhow, the list goes on and on. You’ve ’ probably considered all these things already, if not I encourage you to do so.

What ratio were your original gears? 1.5:1 is pretty high. I went from a 1.6: 1 to 2:1 and I believe it is a big contributor to the performance and efficiency improvement I saw. But I guess if you already have the 1.5 : 1 it’s what you’ve got.

Do you have a good plan for exhaust? Big change going from the V configuration to the inline 6. I used Deangelo and they were good to work with. Gave them all the measurements and info from CAT and they fabbed up a new package and shipped to me. Had a few minor tweeks after we received it but nothing that wasn’t manageable.

Strap your wallet in tight - turbulence ahead!

Excellent! I was under the impression you were just getting started but you’re down the road already. Would be great to see some pictures and have you share your journey. I’m happy to help wherever I can. I can offer up plenty of what not to do’s to maybe save you some heartache.