Bayliner 305/350 swap

[bmarble]

My first post here, this place seems like a wealth of knowledge.

I have a really nice 1993 Bayliner 2250 Bowrider, it was my families and the the entire boat is is near perfect shape, other than the original motor (5.0 mercruiser) has a cracked block. I pulled it, it obviously wasn't winterized. Two years ago a brand new SEI replaced the original alpha one, my uncle said it doesn't even have 10 hours on it yet when the engine block cracked.

So I obviously need a new engine: my options (as of now) are below:

1. I own a 350 from a 1994 Suburban that I pulled from a totaled vehicle with only 80k miles, it was running great when I pulled, seems to me in very good shape.

2. I have been looking at rebuilt long blocks from Mabbco Motors. They aren't far from me so I could save on freight by local pickup and their prices seem very reasonable with a 90 day warranty. I have been looking at a 305 or a 350 (links below).

I am not a mechanic but I can fix most things and I like to do as much work as I possible can, I am fairly certain that I am capable of using either engine options and swapping things over and stabbing it back in, but I am just not super experienced with boat motors and would like some feedback.

Mabbco also offers the the 350 in, 2 bolt, 4 bolt, 2 bolt roller, 4 bolt roller and the 305 with a roller cam. I honestly don't know much about the difference of those.

Link for the 305: https://www.mabbcomotors.com/catalo...995-no-core-required-90-day-limited-warranty/

Link for the 350: https://www.mabbcomotors.com/catalo...olt-no-core-required-90-day-limited-warranty/

 

[Scott06]

My first post here, this place seems like a wealth of knowledge.

I have a really nice 1993 Bayliner 2250 Bowrider, it was my families and the the entire boat is is near perfect shape, other than the original motor (5.0 mercruiser) has a cracked block. I pulled it, it obviously wasn't winterized. Two years ago a brand new SEI replaced the original alpha one, my uncle said it doesn't even have 10 hours on it yet when the engine block cracked.

So I obviously need a new engine: my options (as of now) are below:

1. I own a 350 from a 1994 Suburban that I pulled from a totaled vehicle with only 80k miles, it was running great when I pulled, seems to me in very good shape.

2. I have been looking at rebuilt long blocks from Mabbco Motors. They aren't far from me so I could save on freight by local pickup and their prices seem very reasonable with a 90 day warranty. I have been looking at a 305 or a 350 (links below).

I am not a mechanic but I can fix most things and I like to do as much work as I possible can, I am fairly certain that I am capable of using either engine options and swapping things over and stabbing it back in, but I am just not super experienced with boat motors and would like some feedback.

Mabbco also offers the the 350 in, 2 bolt, 4 bolt, 2 bolt roller, 4 bolt roller and the 305 with a roller cam. I honestly don't know much about the difference of those.

Link for the 305: https://www.mabbcomotors.com/catalo...995-no-core-required-90-day-limited-warranty/

Link for the 350: https://www.mabbcomotors.com/catalo...olt-no-core-required-90-day-limited-warranty/

Take the 350 out of the suburban put marine head gaskets in and brass core plugs. Might need to swap the cam might not. Typically truck cams and marine cams are interchangeable in terms of use. Marine needs idle to 5k power range…

basically strip it to thr long block and swap your marine accessories… prob want to replace your exhaust and intake since it was frozen. Might upgrade to a 4 bbl if you have a 2 bbl carb. Probably would need 2” more prop pitch due to increased hp

 

[bmarble]

Take the 350 out of the suburban put marine head gaskets in and brass core plugs. Might need to swap the cam might not. Typically truck cams and marine cams are interchangeable in terms of use. Marine needs idle to 5k power range…

basically strip it to thr long block and swap your marine accessories… prob want to replace your exhaust and intake since it was frozen. Might upgrade to a 4 bbl if you have a 2 bbl carb. Probably would need 2” more prop pitch due to increased hp

Thanks for the reply, any issue switching to the 350 from the 305 that I could run into?

 

[Scott06]

Thanks for the reply, any issue switching to the 350 from the 305 that I could run into?

only the gear ratio in the drive as mentioned. Generally the 350 would use 1.47 ratio drive and the 5.0 a 1.62 ratio. The 350 will make more power, if it was propped correctly so it was towards the top end of WOT rpm range you will need more pitch or swap the drive.

When I repowered a 4.3 engine /1.81 ratio drive boat to a 5.0, instead of swapping out drives to get the 'correct' 1.62 ratio I just went to a 21" pitch from a 19" and the WOT rpms are perfect at 5k. It would appear the ratios are designed to allow the boat manufacturer to keep the needed props in the typical 17"-21" pitch range

If the drive is new like you say put in the 350, see what WOT rpm you get and adjust prop style and pitch from there.

 

[AShipShow]

You might consider looking at swapping over to the vortec heads and intake while your at it. Just depends on how cheap you're trying to keep things.

 

[Rick Stephens]

That boat will run great on that '94 pull. The cam should be just fine as well. No gotcha's really. Go for it.

Pull your exhaust manifolds, clean them up and inspect for cracks. If you don't see any cracks, then fill the cooling jackets of the mani's with acetone. That will quickly show if there are any cracks as the acetone will leak through the smallest of cracks if they are there.

Scott gave you good advice.

Rick

 

[Scott Danforth]

pull the drive
then pull the motor

as covered above. strip the suburban motor down to short block. throw away all the accessories from the suburban or sell on fleabay.
this is everything bolted to the front of the motor, the starter, alternator, intake, distributor, water pump, brackets, oil pan..... everything

knock out the steel core plugs out of the block and replace with brass ($14 for a kit, $5 for permatex #1)

install felpro marine head gaskets (~$60 a set for the standard, ~$100 a set for the MLS gaskets)

check the heads for warpage. if they are good, you are good to go
check the timing chain for slop. now is the time to replace
stock suburban cam should be fine, swap it with the cam from the 305 if you want. remember, lifters mate with cam lobes for life.

reinstall the heads.

swap over the oil pan, water pump, all accessories, intake, etc. from the busted 305

acetone test your exhaust manifolds for cracks. if they are cracked, buy new

as indicated above, if you want more power, now is the time to swap over to vortec heads. a good used set will be in the $400 to $500 range a new set is $850. it will require a new intake manifold...... and if you want to swap to a 4-barrel, do it at this point.

you can always swap the intake over later

so with the motor you have, you are out under $200 if you do the work yourself, a bit more if you need new manifolds. all under $2k if you want to go vortec.

 

[matt167]

'94 burb will have swirl port heads. Great for torque at low RPM. They are out of steam above 4,000 RPM. Also the burb will have a de tuned engine if it's a 3/4 or 1 ton.. I'd get all the power back with Vortec heads

 

[nola mike]

Thanks for the reply, any issue switching to the 350 from the 305 that I could run into?

as indicated above, if you want more power, now is the time to swap over to vortec heads. a good used set will be in the $400 to $500 range a new set is $850. it will require a new intake manifold...... and if you want to swap to a 4-barrel, do it at this point..

Vortec heads in my pull a parts are $30 for a pair...
And I'm still not sure why they ever made a 5.0 when you can just get a 5.7