Approx. cost to swap 305 and 350 merc engines?

[tmh]

OK, to make a long story short....I have a heavy 1985 19' BR (maybe 3100 lbs) with a Merc 305 2-bbl Alpha one 200 hp, I think 1.65 ratio, not sure. Gets me about 41 mph w/ 17" prop WOT 4200. I have done ALL recommended to get a bit more out of it....that's all it has and can't get to proper WOT range w/ 19" prop. I love the boat (me and my boys re-did the deck, and all the seat cushions and much more so we're attached to it emotionally!).

So, I see a boat for sale locally (know the seller/dealer a bit). It's a lighter 1985 19' BR (Bayliner)and it has a Merc 5.7L (350 i think) 260hp engine. The boat goes over 60 mph due to light weight and more shallow hull - and bigger engine. I'd be afraid to go that fast in a little boat with any chop at all! I DON'T want the Bayliner, just the engine from it! The boat itself isn't a wreck, butmine is a much nicer interior and a heavier,deeper V so smoother ride in chop.

So, my thought is if I can buy that boat cheap, then switch engines I'd be at least into the mid 40's, where I want to be and the other boat would still get close to 50 mph which is plenty in that hull! I'd then sell the other boat (now wit the 200 hp engine).

About how costly would it be to have the engines swapped? I have read here that they swap fairly easily, but I can NOT DIY and would hire it out to someone - maybe an individual I/O repair person. I guess we can assume around $45-50 per hour or so.

Again, I'm not asking about the buy/sell costs for the other boat, just the cost to take each engine out of the current boat and put it into the opposite one. I assume it's mostly labor costs, plus maybe some parts to make it work? Anyone care to guess ABOUT what it might cost? I'm just looking for a guess with somewhat limited info. I understand. I'll look into it more if the estimates look doable to me.

Thanks for the help, as always.

 

[Bondo]

Re: Approx. cost to swap 305 and 350 merc engines?

Anyone care to guess ABOUT what it might cost?

Ayuh,.....
If there's No Gotchas,.....
It can be Easily done in a Day's Work......
Provided the Mechanic has the usual Shop environment(air tools, lift, etc.)....

 

[tmh]

Re: Approx. cost to swap 305 and 350 merc engines?

Thanks so far. Sounds reasonable.

One more option is to buy a "crated" engine again a 350. I am not sure which components I'd have to change going this route OR who is a reputable, yet inexpensive dealer of replacement engines is. I see a few on eBay with very good feedback, cost $1200-$1500 plus $200 shipping.

I could then sell mine for maybe 1/2 that and only be out $600 plus labor.

Choices, choices. Or I can do what my wife says and leave it alone........nah!

 

[tmh]

Re: Approx. cost to swap 305 and 350 merc engines?

One more question about 305 to 350 swap. I see "pre-'87" and such - do i need a 1985 vintage 350 engine to make the swap? Or is there a range of years that would work fine? Thx.

 

[Bondo]

Re: Approx. cost to swap 305 and 350 merc engines?

Ayuh,....

It would be Easiest with a 79 to 86 vintage block.....

 

[tmh]

Re: Approx. cost to swap 305 and 350 merc engines?

OK, moving along here.... I was told by a local mechanic he'd charge about $500 to swap in a 350 (not exchanging the two like I was discussing, this is I buy one and he swaps it). He also mentioned some things i had already heard may help my 305 get a bit more (4bbl carb - maybe 2moh, some different cam - I didn't really 'get" what he was referring to). This and/or the 350 and he thinks i'll get maybe 3-5 mph top end improvement.

So I see the following 350 on eBay, find out it's pulled from a 1985 Formula boat that had a bad transom. Within 100 mi. drive for me.

http://cgi.ebay.com/ebaymotors/ws/e...m=280211455095&ssPageName=STRK:MEWA:IT&ih=018

Assuming the link works or you can cut paste the URL, please help me out with a few things.

1. Does this 350 appear to come with a 4bbl carb?
2. This 'cam" upgrade th mechanic mentioned, would this 350 come with an "upgraded" cam vs. my 305?
3. Does this one llisted have more of what is needed for the swap than a typical "crate" engine - so i can sell my 305with most items still with it?

IF I can use this (or similar), maybe buy for $1000, $500 to swap then sell mine for maybe $500 or so, then i'm roughly $1000 all-in with a 350. However, do i need to do more like exhaust, intake, etc. to get the most out of the 350? Or is that all on the motor I linked to?

Sorry for the stupid questions, but I am learning on the go....

 

[bruceb58]

Re: Approx. cost to swap 305 and 350 merc engines?

If I was going to go through all that effort and cost to put in a motor, I would put a crate motor in.

If you decide to go the ebay route, what year is the motor and how many hours are on it? When was the last time it was actaully run? Was the motor fogged before it was stored?

The other thing you have to ask yourself is this really worth doing in a 1985 boat? Might be better off buying a newer boat with the 350 engine in it already.

 

[John_S]

Re: Approx. cost to swap 305 and 350 merc engines?

1) Can't see it in picture, but if it is a mag of that year, it has a 4brl. Probably Q-jet.

2) Don't know of any cam upgrade. I thought there was only one flat hyd and one hyd roller sbc cam for mercs. Maybe the 305s had a "lessor" cam??? I'd check via part numbers on one of the part sites.

3) Yea, but you won't get much for the 305, especially if yours is "tired".


FWIW, I wouldn't putz around and change in a used engine. Go with a new or quality rebuilt long-block 350. A pre-'87 350 with vortec heads/4brl will about 280hp at the prop.

 

[tmh]

Re: Approx. cost to swap 305 and 350 merc engines?

Thanks to all for the info. I guess the problem with a new engine is it then really makes it a foolish project cost wise (vs a foolish project hassle wise if I buy used!). I may very well do nothing, but I'll keep checking into it for a while, mulling the options and wishing it were spring here.

I did check the eBay feedback of the guy selling the 350 Mag enginje and he gets great reviews so i assume he's not trying to sell anything other than what he says it is. Even still, it's a 20+ year old engine, like mine.

One more question, IF I want to buy that engine (or any) how do i know it fits easily for my boat.....meaning do i need to match certain years, serial #'s or whatever to know? I read some discussions of folks repowering and the mechanic running into issues and needing to fab pieces, etc taking forever and being costly! I don't want THAT!!!

 

[jaxnjil]

Re: Approx. cost to swap 305 and 350 merc engines?

i missed the point of the swap in first place
whats wrong with running a 17inch pitch prop and what can you do at 47 or so mph you cant do at 41 mph?

 

[Bondo]

Re: Approx. cost to swap 305 and 350 merc engines?

Ayuh,....

1),.. The 350cid., 260hp Merc of that vintage Is a 4bbl. equiped motor.....(btw, there were No Mag motors then)

2),.. Forget the Cam upgrade,....
Swapping the Cam in your 305 will net you little or No real usable hp gains... Key word is Usable...

3),.. Ayuh,.... That motor would be a Plug & Play motor for Your boat....
Using a Crate Motor,... You'll have to strip off all of the Marine Accessories from the 305, for the 350...

One more question, IF I want to buy that engine (or any) how do i know it fits easily for my boat.....meaning do i need to match certain years, serial #'s or whatever to know?

Ayuh,.... There sure Are some Differences,......
Just so I don't have to type 8 or 10 pages of Info, with my 1 typing finger....
Find what you Think you Want,....
Then come back,+ Ask about whatever it is,..??

 

[tmh]

Re: Approx. cost to swap 305 and 350 merc engines?

i missed the point of the swap in first place
whats wrong with running a 17inch pitch prop and what can you do at 47 or so mph you cant do at 41 mph?

You can go "waaahooooo".

There is a reason most new bowriders go high 40's into the 50's - because that's what people want. WHY? It doesn't really matter.

bondo, thanks again. i emailed the seller of that engine and he'd put it in for me for $400. he's a "gear head" and has bought/fixed up/sold boats and autos for years, for profit and also as an obsession. I think I may take him up on it IF I can win it on ebay for not too much.

 

[tmh]

Re: Approx. cost to swap 305 and 350 merc engines?

Ayuh,....

1),.. The 350cid., 260hp Merc of that vintage Is a 4bbl. equiped motor.....(btw, there were No Mag motors then)

Bond-o, good point on the Mag engine. Although I don't know what "Mag" means, the seller said the engine S/N indicates it was manufactured between 1987-1992. So it's either not a 1985 boat or the boat was repowered I guess.

Were Mags made then? Is a "Mag" any better than "non-mag"? Why?

 

[Bondo]

Re: Approx. cost to swap 305 and 350 merc engines?

Were Mags made then? Is a "Mag" any better than "non-mag"? Why?
Although I don't know what "Mag" means,

Ayuh,...... Honestly,..... I don't either....

I've noticed that the "Mag" was added to the 350 name about the time Merc went from the old Rottenchester Carbs to the Merc/ Weber/ Edlebrock/ Carter clone AFB Carbs,.... No Idea when that started happening...
It's rumored that the "Mag"s use somewhat stronger components,...But I've seen No Proof of that,...
Also,.... I've never seen any HP figures hung on the "Mag" motors.....

Unless You want to go pour through piles of Parts Listings to find the differences,....
That's about the Best I can do, 'cause I'm not willing to spend the time Looking.....

 

[John_S]

Re: Approx. cost to swap 305 and 350 merc engines?

A year ago, I did spend some time going through many parts manuals and service manuals on the quest to determine what was different. This was looking at the post '87 upto the gen+ vortec engines. This was looking at only carbed versions. The main difference between a 350 Mag and the equivelent year 5.7LX, is the intake manifold, carb jettings, and timing modules. Some of these were even the same on particular years. Now the interesting part is, they are both rated at 250HP at the prop, from the service manual. For the most part, I believe the 350 MAG was good marketing to the go-fast crowd.

The 350 MAG might have received the roller hyd cam before the LX, but there isn't any hp difference.

 

[Windykid]

Re: Approx. cost to swap 305 and 350 merc engines?

If this makes a difference:

1987 was the year GM changed the bolt patterns(angles) on the engines(pre vortex) this caused the old manifolds and exhaust to not bolt up. This was due to the truck and car market changing to throttle body's fuel systems OBD1.

 

[tmh]

Re: Approx. cost to swap 305 and 350 merc engines?

If this makes a difference:

1987 was the year GM changed the bolt patterns(angles) on the engines(pre vortex) this caused the old manifolds and exhaust to not bolt up. This was due to the truck and car market changing to throttle body's fuel systems OBD1.

hmmmm.......maybe that DOES make a difference. If it adds cost/hassle to the install I may not go forward with it. Anyone have an opinion on this?

 

[Bondo]

Re: Approx. cost to swap 305 and 350 merc engines?

If this makes a difference:

1987 was the year GM changed the bolt patterns(angles) on the engines(pre vortex) this caused the old manifolds and exhaust to not bolt up. This was due to the truck and car market changing to throttle body's fuel systems OBD1.

Ayuh,..... Sorry Windykid,.....I think you're Wrong,...
Other than the change of angle of the Intake Bolts(the 4 center 1s).....
The Exhaust hasn't changed....
The other Big Change that year was the Crankshaft Bolt Pattern went from 3, 1/4",... to 3".....

 

[Coors]

Re: Approx. cost to swap 305 and 350 merc engines?

Ayuh,..... Sorry Windykid,.....I think you're Wrong,...
Other than the change of angle of the Intake Bolts(the 4 center 1s).....
The Exhaust hasn't changed....
The other Big Change that year was the Crankshaft Bolt Pattern went from 3, 1/4",... to 3".....

Yep.
the crank change was one piece to two, I think. Somewhere in that range. 88 is two piece, I think.

 

[tmh]

Re: Approx. cost to swap 305 and 350 merc engines?

Yep.
the crank change was one piece to two, I think. Somewhere in that range. 88 is two piece, I think.

Guys, I am close to a decision on buying this engine. I'm trying to understand how tough a swap this is......assuming my engine is a 1985 305 and the one I'm buying would be a 1987-1992 vintage 350. So, basically, what changes in the install or modifications will be needed. I won't understand the specifics, likely, just trying to ballpark how much mod work the mechanic will need to do.

So far, no bids so it's at $500 but the eBay reserve isn't met....so I'm hoping to get it for $1,000 or so. My local mechanic says I can't go wrong at that price if it's in decent shape. It's the whole engine, not just the block. I called two shops and one guy who does marine work on the side. Looks like somewhere between $350-500 to install. I may go with the "on the side" guy, NOT to save $$$ but because he'll let me help and I'd love to see how it's done.