Thanks Rick
The thing runs flawless so something tells me leave it alone for now! It doesn't look like it's ever been apart so I assume it's all stock inside. I love the boat and have two extra complete dog clutch outdrives so I'm keeping the OMC. I'll probably go through the motor next winter just because I don't know what it looks like inside. I'd like to get 73 out of it without tearing up my outdrives. Any recommendations on a good cam for a rebuild?
Mike
Howdy Mike,
Well, You would want to select a cam that is "RV" type or "truck" etc.... You want to be able to run about 5500 or less....... A Cobra (and any other stock Mercruiser etc) really wants to turn 5500 or less. You can make a LOT of HP at 5500.
My brother bought my 87 Four Winns Liberator new with the 460/Cobra. In the 90's he had the engine rebuilt after a freeze "incident" (he didn't drain the block because it never freezes in Ca!!!) Amazingly, his insurance paid for the damage.
The Shop (in Redding, Ca) that did the engine was sort of a Big Block Ford specialist. He put a different cam in the engine but I don't think he did much else. He stayed with the OEM carb. Evidently it was big enough. He also didn't put a different intake manifold on it.
You would want to be fairly careful how much power you run though I would think. I don't think you can break the Cobra that was designed to go behind the 460................ I would be afraid of spinning the coupler. They're anywhere from $420-500 and you have to pull the engine to replace them.......
Have you tried to find manifolds? I haven't looked for manifolds for about 10 years.
When I pulled the 460 and Cobra drive out of my Liberator in 2006, Couplers were not available at all at any price. Exhaust Manifolds were new old-stock only and scarce. I could only find one at a time and they were around $1600. There were welded SS manifolds but they cost more than an engine rebuild. And without a coupler I was dead in the water........
That's when I decided to look for a replacement engine + drive.
I paid $5000 for a complete 1997 454, Bravo III package (with 120hrs since new) complete with controls and gages out of a 98 24ft Bayliner that had a tree fall across the bow. The install was pretty easy. All the holes in the drive cut-out match (except I had to drill 2 additional holes for the Bravo gimbal)
It's a tad slower in top speed, 55-57 now ( 60 before).........but now, it comes out of the hole like a ski boat. Not bad for a boat that weighs around 4500lbs........
(I suspect I could get more speed if I rebuilt the engine and removed the rev-limiter [4700] )
By the way, I was able to sell all the OMC "stuff" over a 2-3 year period including the dissembled engine($150) for a total of $3500 (the BIG Cobra drives are pretty valuable....I got $1400 for the drive alone.) .......... So if you ever decide to switch to a Mercruiser BB + Bravo I/III, Selling all the OMC "stuff" would net you a lot if you were patient. I shipped my drive all the way to the East Coast.
I am sure you know this ..........but when ever you change your drive oil, make absolutely sure you fill the drive in accordance with the OMC service manual. (via the "FILL" port,....NOT the drain port.........lot of people have come to iBoats asking why their drives self destructed (after an oil change) AND Don't let any dealer change it either (unless you can be certain they know what they're doing!!! My brother had 2 different dealers fill his wrong and both ended up replacing the drive!!)
