New guy with some drive compatibility questions...
 

Alright, somewhat new to the marine world, picked up a Checmake Persuader 219 for next to nothing in awesome shape. Has an OMC 460/Cobra engine/drive. Not sure on all the engine details (bought it from a lady who's husband passed away) But it does have some visible bolt on's. Weiand intake, Holley 800 double pumper, MSD ignition, Holley blue lift pump. Went through everything on this boat when I got it. Took it out for the first time last Sunday, and although it ran great, I was only limited to about 57-58 mph. Guess I was just expected a little more out of it? Anyway, I'm gonna make some subtle changes this season to see if I can at least get it into the 60's.

Now my real question, let's say I wanted to ditch this OMC setup this winter and go with a Bravo 1/BB CHEVY based engine, what am I looking at for work? Transom need to be re-glassed/re-cut? What do I need to do to adapt a Bravo drive to a BBC? I'm ultimately shooting for 500-550hp which I know is the upper limit of the Bravo drive but I'm ok with being nice to it until the top end. The engine I build probably won't be "marine based" so that's where my questions come in on drive compatibility. I come from the diesel performance world so I'm completely lost here... And it seems MUCH more difficult to find answers on this subject. Maybe I just don't know where to look? Transmission compatibility is easy in the automotive/diesel world. Answers seem to be few and far between in the marine world...

I know now my plan here isn't really "cost effective" but I really like this boat, and even more, I like building things myself...

Open to all comments, concerns, advice, and a$$ chewings Lol

I am exactly in the shoes you are. I got a deal on a boat and unfortunately it has a King Cobra drive but fortunately a cone clutch version. I did the same and looked into a swap and they make a kit to swap over from an OMC to a Merc on the transom with no cutting, and your costs will depend on what drive you want. You need to find out if it is a King Cobra or not as they will take more power over the dog bone clutch as what I have been told. I just built a motor for mine and it dyno'd at 621 HP and 670 ft lbs of torque. I ended up buying a complete spare setup including transom for a swap out or for parts for a great deal as parts are scarce. My plan is to not flog the outdrive and go easy. Will have it out on the water for the first time in a few weeks so hopefully it will hold together. This is my first boat and do all of my own work and I come from a hot rod/drag racing background and putting this boat back together and upgrading it has been a lot of fun and have learned a lot.

So I'm not "positive" but from what I've been told, it is not a King Cobra. I've searched the numbers on it and have come up with nothing definitive as well... could someone tell from external appearance? Or some other way? I have a few pics of it...

Also, what are some of the specs on your new engine build? What did you start with??

Yes you can tell if it has a lump on the top cap. Also it needs to be at least a 1990 I believe?
http://i393.photobucket.com/albums/p...psrh124hzg.jpg

You can check out the motor build on this thread

http://www.offshoreonly.com/forums/g...motor-fun.html

so I researched all afternoon and what I came up with ultimatley is that there are 3 different variations of the cobra, standard cobra, early king (dogbone clutch), and later king (cone clutch). Apparently I have the early king. It's the same upper as the standard cobra but a much beefier lower unit... from what I've been finding, this drive might actually hold some power if I keep it adjusted/maintained well... I'm not a big Ford fan but this does have me considering just building the 460 until something goes boom 😂 (Here's the drive comparisons OMC Cobra, King Cobra, OMC Important Info about OMC Cobra, King Cobra )

Where did you you find your engine for that build? I can't find anything but complete crate engines for 7-20k in the 500+ ci range...

I completely rebuilt that from the motor that came with the boat and only used the block, heads, crank and rods. Everything else is brand new including all the valvetrain. There are a lot of smart guys on this board that could chime in for sure for that 460. I say just drive it and have some fun until something breaks then fix it. It sounds like you are mechanically inclined and these old boats are like old cars, pretty basic. I bought a real shop manual off of e-bay for $40 and it has got to be my best purchase LOL. Just the wiring diagram is priceless.

Keep the drive and get the engine healthy. I'd expect it to be faster, should be able to run that speed on 7 cylinders.

Ok, the 460 ford is a decent clone of the big block chevy. You can get some decent power out of them. The cobra and king cobras are ok drives too. Not real hard to find parts for. The main thing though is all modern common drives fit the same keyhole cutout. You can unbolt a cobra or a Volvo sx and put a merc alpha or bravo in the same spot. No glass work. If you really want to convert to merc, start looking for a junk whole boat. The ones that had the blocks crack and let the interior disintegrate. I found one for 1500 and sold trailer with hull still on it for 300. Got every single part I needed and got to completely dismantle it so I knew what went where. Much easier to do that way than buying a gimball housing and a drive and then looking for all the little stuff...and it is a dog clutch, not dogbone clutch.