repower a 28' Flybridge

Bob on This · Dec 12, 2008

Hi everyone.
New to this forum.

I am looking at a 28' Flybridge that looks like it's in good shape for an older (1980's) boat.

The one thing that bothers me it this, the boat has twin Merc 470's with V-Drives. One engine is dead, but repairable.
I know of some of the problems with these engines, and so if I keep them I would need to add a maine alternater, raw water pump, and a 4" coolers. Maybe a new ignition would also be in order.
So, spend about 5K to bring these two up to par, or repower with a couple new 3.0 liter Merc for around 10K.

Anyone on here have a similar deal? or maybe just some ideas?

I will keep my 97 Wellcraft Excel 260 (Bob on This II) to use and keep myself on the water until this prodject is completed, so I am in no hurry.

Thanks in advance to any advise you care to share.

Bob

QC · Dec 12, 2008

Re: repower a 28' Flybridge

Hey, Bob, welcome aboard. I moved your thread over here 'cause you'll get more specific engine info here. Good luck. I think I'd try an older in-line six if you can handle the length . . . Not sure a 28 footer would do well losing the combined 60 horsepower . . .

legoman67 · Dec 12, 2008

Re: repower a 28' Flybridge

have you checked the transom, i bought a 29' 1974 a little while ago, transom seemed soild, even did afew core samples around the center, then i pulled the transom sheild off...

well you can guess the rest..

check out the restoration forum 29' carter safari.

Bob on This · Dec 12, 2008

Re: repower a 28' Flybridge

Hey Legoman, thanks for the tips.
BTW, nice little prodject you got going. I read your thread, WOW.

The boat I'm looking at is very similar you yours, and is accually up in your corner of the world.

I was looking for a very low cost "prodject" boat to work on for a couple years and then go explore the Northwest around your area.

We live in the four corners area (Colorado, New Mexico, Azizona, Utah.

The "prodject in in Washington, and if we can make a deal, I will go up and trailer in back. When finished, bring it back, and explore the San Juans.

We have never had a big problem with wood rot, basicly we don't leave our boat in the water, and the air is so dry here, that everything drys out quickly.

After seeing your transom, now I'm worried. Guess I can ask to do a core sample or two. I,m guessing the stringers should be checked as well.

Does the fact that this boat is an inboard V-drive without holes in the transom, somehow make this type of porblem less likely?

legoman67 · Dec 12, 2008

Re: repower a 28' Flybridge

hey, we got ours in seattle aswell, im not very familiar with velvet drives, but if nothing is attached to the transom, then i cant see it being of much importants. make sure you do samples near connections and bolt holes. that was my mistake..

maybe someone else who has worked with velvet drives can enlighten us to the key areas for rot checking. besides the stringers.

Bob on This · Dec 13, 2008

Re: repower a 28' Flybridge

Thanks, I'll see if I can tell when I get up there. I'll let you know when we plan the trip, or "IF" we plan the trip.

Anyone else done this engine swap?
Are the flywheel and housing the same SAE type and will the V-drives bolt up?

I have not heard back from the broker on the model of the V-drive, so I guess what I'm asking is the flywheel housing the same on the old Merc 470 and the new Merc 3.0 or 4.2?

Also, is there a reason the smaller engines are only listed as I/O on the Merc wed site? Not as in-boards.

Thanks
Bob

Bondo · Dec 13, 2008

Re: repower a 28' Flybridge

so I guess what I'm asking is the flywheel housing the same on the old Merc 470 and the new Merc 3.0 or 4.2?

Nope,...

The last 2 are Chevy patterned,+ I believe the 470s were Ford patterned, or possibly Merc. patterned...

That's not at all insurmountable though,...
The Chevy patterned flywheelcovers are a dime a dozen...

Bob on This · Dec 13, 2008

Re: repower a 28' Flybridge

Thanks, good info.

What about the drive coupling and/or input shaft? Should I plan on a new coupling anyway?

Thanks
Bob

Don S · Dec 13, 2008

Re: repower a 28' Flybridge

I really wouldn't even try to put two 3.0L engines in a 28' boat and expect it to go at all. But if you want to go thru with it, you will need a 3.0L coupler. They are designed for the engines crankshaft. The splines for the drive are all the same.
You will also have to change the gear ratio's in the drive to a 1.98. The 470 ratio will never work with a 3.0L engine and that big of a boat. You may have major problems getting the exhaust pipe that hooks to the transom shield to fit the 3.0L engine.
You are about to spend a lot of money to find you don't have anything worth using.

Bondo · Dec 13, 2008

Re: repower a 28' Flybridge

Ayuh,...

If it's anything your Up to,...

Converting to V-motors would bring a much Better results....

Bob on This · Dec 13, 2008

Re: repower a 28' Flybridge

Yes, I'm also think maybe more power, not less.
We do most of our boating on Lake Powell in Northern AZ and Southern Utah.
Lake Powell is about 4000' ASL, and Navajo lake (about 1/2 hour from home) is even higher at 5500' ASL.

That being said, we do 90% of our traval at hull speed with a little running at 20 - 23 MPH so the wife can wake board.

I fully understand the disadvantages of low HP and tring to run an engine too hard.

There are people out there that claim the way the HP was calculated back in the 80's was flywheel HP and that the newer 3.0 is calculated as prop HP, and that they are very simmilar in performance.

You would think that being a saleman for a Caterpillar dealer, I would have a great deal of opertunities to repower with a couple diesels, but alas, here in the desert southwest, we don't do a lot of marine engines.

Also, diesel fuel is not easy to find at the local marinas.

At any rate a couple small V6 engines maybe the cat's meow....

I will just have to see where the budget is if we get this little prodject.

I may need to just update and overhaul the 470's and keep them. I understand they are not BAD engines, just need to add a few mods to make them more useable.

Thanks
Bob

Bondo · Dec 13, 2008

Re: repower a 28' Flybridge

I am looking at a 28' Flybridge that looks like it's in good shape for an older (1980's) boat.
I may need to just update and overhaul the 470's and keep them. I understand they are not BAD engines, just need to add a few mods to make them more useable.

Ayuh,....

I'd look for a Different boat,....

Why set yourself up for Disappointment...

Those motors have been Out of Production for 20 Years...

abj87 · Dec 13, 2008

Re: repower a 28' Flybridge

If the price is good go for it. If there taken care of they can run for years.

Bob on This · Dec 14, 2008

Re: repower a 28' Flybridge

There seems to be people on both sides of the fence.

I guess I'm with you. If the rest of the boat is in good shape, and I can get it
for the right price, even though I need to OH and upgrade, I think I will be OK.

From what I can see in the photos, It looks like they took really good care
of the cosmetics, but I have known people that are very good with one part
of boat ownership, and not so much with the other.

I have no plans on buying or even putting money down on this thing until
I get a chance to look her over.

I know already that both engines need to come out. One has a broken timing
chain (pistons may have slapped the valves) and the other has some problem with the V-Drive.

My plan would then be, to OH both engines and both transmissions.
I have a fairly good grasp on the engine OH costs, does anyone have a
WAG on the cost to HO a V-Drive?

Only time will tell.

Thanks for all your input.

Bob

Don S · Dec 14, 2008

Re: repower a 28' Flybridge

Think about one thing with those engines. They are an aluminum block, open deck design. The block is Mercruiser, not ford or chevy. The head is a Ford 460. Parts are expensive, and some exhaust parts are NLA from Merc and not asftermarket.

WAG on the cost to HO a V-Drive?

Huh????????

Bob on This · Dec 14, 2008

Re: repower a 28' Flybridge

Thanks, I see your point.
I guess that's why the one guy told me is about the same price for new 3.0 compared to exchange.

WAG (Wild A*@ Guess)

Bob

Don S · Dec 14, 2008

Re: repower a 28' Flybridge

I understand what WAG stands for, but what about HO a V-Drive. I didn't understand HO, after rereading I guess you meant OH (overhaul).

Hard to say, don't even know what type V-Drives they are. If they are BW, a complete OH kit is something like 2-3 hundered bucks (I think) and has the discs & seals. plus whatever parts are bad in them.

muskie hunter · Dec 14, 2008

Re: repower a 28' Flybridge

Bob on This said:
Hi everyone.
New to this forum.

I am looking at a 28' Flybridge that looks like it's in good shape for an older (1980's) boat.

The one thing that bothers me it this, the boat has twin Merc 470's with V-Drives. One engine is dead, but repairable.
I know of some of the problems with these engines, and so if I keep them I would need to add a maine alternater, raw water pump, and a 4" coolers. Maybe a new ignition would also be in order.
So, spend about 5K to bring these two up to par, or repower with a couple new 3.0 liter Merc for around 10K.

Anyone on here have a similar deal? or maybe just some ideas?

I will keep my 97 Wellcraft Excel 260 (Bob on This II) to use and keep myself
on the water until this prodject is completed, so I am in no hurry.

Thanks in advance to any advise you care to share.

Bob

Why would you want to mess with that old tug when you have a 97 wellcraft Excel? In my opinion the excel is a much better boat anyway.Just my 2 cents.

Steve

chiefalen · Dec 14, 2008

Re: repower a 28' Flybridge

http://forums.iboats.com/showthread.php?t=285663&highlight=3.7,+470

Post # 14 Should tell you everything you will need to know.

Bob on This · Dec 14, 2008

Re: repower a 28' Flybridge

Wow,
I guess I should look for another boat

repower a 28' Flybridge

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