OMC 460 rebuild

[HT32BSX115]

Howdy all,

Has anyone rebuilt an OMC BBF 460 in recent times?

I'm looking for ideas.


Thanks,

Rick

 

[Don S]

Re: OMC 460 rebuild

You might want to look around at the availability of Exhaust risers and manifolds before you start putting any money in a 460. Last time I heard none were available. No reason to rebuild an engine if you can't get manifolds. And if you boat in salt water and the manifolds are over 5 years old, you are due for new ones. So look around before you start on the engine.

 

[HT32BSX115]

Re: OMC 460 rebuild

Hi Don, (Just flew over your area a couple times last week!)



Doug Russell Parts just told me that manifolds and risers will be available next spring. Presumably new manufacture.

Mine are in excellent condition and have never been in salt.


The coupler is another problem. They said it's 'NOT AVAILABLE"

There's nothing wrong with mine but it would be nice to have a spare available. I'll grab the next used one I find probably.


I guess I should start considering a repower....I think the adapter for OMC to Merc is about $800 or so.

Have you done any of those?





Thanks again,

Rick

You might want to look around at the availability of Exhaust risers and manifolds before you start putting any money in a 460. Last time I heard none were available. No reason to rebuild an engine if you can't get manifolds. And if you boat in salt water and the manifolds are over 5 years old, you are due for new ones. So look around before you start on the engine.

 

[Don S]

Re: OMC 460 rebuild

I forgot about the coupler, someone here found some brand new ones in Florida I think, but I would guess they are gone already. Those manifolds have been promised several times, but no show on any of the other promises, so take that info with a grain of salt.
Another problem is gear sets and drives for the big blocks. They are about as hard to find as couplers and manifolds.
Makes you glad you own an OMC doesn't it :/

 

[HT32BSX115]

Re: OMC 460 rebuild

Not so glad!


The drive has less than 200 hrs on it.... and has never been driven into the ground or anything else for that matter.


I knew this would be a problem (After I bought the boat of course!!!) My brother bought the boat new and took very good care of for many years. The riser gaskets leaked into the exhaust manifolds for about 3 years.....little bit of water after shutdown.....It would crank hard immediately after shutdown. It ran fine otherwise. All it needed was new riser gaskets. (3 years ago!!)

Classic case of (me) not doing my homework!!


It's possible that some of us only learn the hard way!!(Hey a new signature!)



Regards,


Rick

 

[imported_rosco]

Re: OMC 460 rebuild

you could always fabricate a block off plate for the exhaust and run through hull exhaust. then any manifold would work.

 

[Don S]

Re: OMC 460 rebuild

you could always fabricate a block off plate for the exhaust and run through hull exhaust. then any manifold would work.

Not exactly, in an open boat you could run dry headers since the engine is exposed to the air. Then you have a place for the heat to go.
But to have an engine compartment with a dry exhaust manifold is a big No-No.
Talk about a fire hazard. Glowing exhaust manifolds! ! ! ! Woa.

Even thru the transom exhaust is water cooled.

 

[HT32BSX115]

Re: OMC 460 rebuild

Yeah I would never try dry stacks on this boat! It already has thru hull exhaust anyway (Plus a y-pipe and electric diverters)


I could run a set of these: http://www.boatheaders.com/

They are stainless steel jacketed header/risers. BUT they are $2000+ and I'll still have the same coupler, and wonderful OMC drive! I don't have a problem with the 460. It's a good engine. If I could keep it and bolt a Volvo drive on the back I would.


I just got off the phone with a Volvo dealer .

$17,000 + install for a 320hp Volvo 5.7Gxi + Duoprop.
$20,500 for a 375hp 8.1Gi + DP

New with warrenty etc.

Not a bad deal. I could not buy a boat like this with a new engine/drive for this money I suppose. They said they could do it in 2 weeks or so......I'd want it by next summer ........


I'm a glutton for power !




Don,


My 460 is rated at 340hp. at 5000rpm it would do 60mph (GPS) empty.

It also comes out of the hole pretty good.

Would I be disappointed with the 320hp 5.7Gxi + DP?

 

[Don S]

Re: OMC 460 rebuild

5.7GXi would probably be about the same as your 460, except you would get better out of the hole and much better economy. Only 50 MPH WOT when empty but that is the best you will get with the DPS Drive, at higher speeds you need a different drive to prevent porp blowout.

8.1Gi DP----- Probably couldn't get you to stop smiling for months.

8.1GXi DP 420HP ----- Probably couldn't get you to stop smiling. Period.

You'll have to upgrade to the DPX drive to go over 50MPH however.


http://www.volvo.com/NR/rdonlyres/E488945B-F010-4EA4-A7EE-A83B5FB17AAE/0/81_DPS_07.pdf

 

[lilmandavis]

Re: OMC 460 rebuild

ive rebuilt a few 460's before. a new coupler is still avaible. but start looking at about 30-40 gph on the fuel depending on how big the boat is. make sure you buy the oem cam though and go through and lose the bolts and put in studs. make sure you fit the intake gaskets good or they will suck in. i use the indian head shellac. ever since ive used that on all bb engines. silicone sucks, especially when its gobbed on by some a**
call ken at southwest marine he can get the couplers. 239 332 2166 his prices are a little higher. but he has great service and factory parts. make sure and throw away the valve springs and replace them.

 

[HT32BSX115]

Re: OMC 460 rebuild

I have considered using Blue Thunder aluminum heads with BBC exhaust flanges on them...... roller rockers, a custom Crane cam....and an Edlebrock performer aluminum intake manifold. This coupled with BBC aluminum manifolds and risers saves nearly 200lbs AND probably gives me quite a bit more power.

There is absolutely a WEALTH of info out there on marine 460's .......They are still pretty popular in hot jet boats.


All this is good I suppose.....But there's still that scarce coupler. And I even thought about that. I have access to a complete machine shop. I have considered getting a custom crankshaft built with a BBC bolt pattern on the back........That gives me the ability to use a Custom flywheel and BBC coupler...........I'm surprised that someone hasn't tried this already.......but it still leaves me with the limited and dwindling parts availability for the 1.43:1 King Cobra drive......this could be a sho stopper......not good after spending a fortune tricking out the BBF


There's nothing wrong with my coupler. and manifolds. right now... SO I may just long block my 460 and use it a couple more years

Then I have my eye on that Volvo 8.1GXi!!....Or a Mercruiser BB and Bravo.....I have time to decide on a choice....



By the way.....in it's present condiion I was only getting 4200 rpm at WOT and exactly 50mph on my GPS........This on a 20p prop that produced 60mph at about 5000rpm before! (All stock)