i just won a 18 foot sportfire on ebay.. here is the problem it was a merc 485 motor that is stuck .. by the way the boat cost me only 450.00 its in good condition..but my ? is what typ of motor can i put in it ? can i make it an outboard? can i put a bigger inboard ? or should i just rebuild the one in it now? or where can i find a motor for cheap? thank you for your help
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help
- Thread starter skylervee
- Start date
here maybe someone can help me with this is this a checkmate sportfire because all the once i see so far have been outboard motors im picking this boat this week and would like to know the best way to go about fixing it the motor is stuck ... suould i rebuild or get a beter motor .. this motor for what im told is a merc. 485? can some give me some advice...
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Chris E
Well-known member
wow - quite a project there.
first off, needs gimble bearing, u-joints i'm assuming full bellows, shift cable, etc. etc.
if the engine is junk - and it looks like it - get rid of it. this motor was mercurys futile attempt at a mid size motor until the 4.3L became available. its a 3.7L 4 cyl. Ford cast iron cylinder head (from a 460). mated to an aluminum block. it had to have closed cooling. the engine doesn't have an alternator per se - it is a stator on the front of the engine. they came in a variety of horsepowers 165, 170, 188, 190 the latter are 4bbl carbs. they are loud vibration prone turds. more importanatly parts are starting to get scarce for these gems, especially the heat exchanger.
if you spend some time you can problably find a newer 4.3L 4bbl at 205hp that will work a lot better, although they vibrate a bit too look for a complete package (drive, t-plate and motor). even better throw in a 350 v8 for some real fun if room permits (it should)
enjoy your new toy. it'll be awsome when its running and back in the water.
first off, needs gimble bearing, u-joints i'm assuming full bellows, shift cable, etc. etc.
if the engine is junk - and it looks like it - get rid of it. this motor was mercurys futile attempt at a mid size motor until the 4.3L became available. its a 3.7L 4 cyl. Ford cast iron cylinder head (from a 460). mated to an aluminum block. it had to have closed cooling. the engine doesn't have an alternator per se - it is a stator on the front of the engine. they came in a variety of horsepowers 165, 170, 188, 190 the latter are 4bbl carbs. they are loud vibration prone turds. more importanatly parts are starting to get scarce for these gems, especially the heat exchanger.
if you spend some time you can problably find a newer 4.3L 4bbl at 205hp that will work a lot better, although they vibrate a bit too look for a complete package (drive, t-plate and motor). even better throw in a 350 v8 for some real fun if room permits (it should)
enjoy your new toy. it'll be awsome when its running and back in the water.
daren34
Member
new motor
hi bigdave has the same boat in an open bow and he took out the old 470 and installed a 305 chevy
we had a complete pakage out of another boat
the v-8 is real heavy in the back
good for wake boards bad for slalom skiers
I have an eluder with the 4-bbl version of the 470 at 190 hp
i run about 53 or so and pull skiers good
you can still get a reman short block from merc if you go that route
this is a wet sleve aluminun block and you would have to have the right equipment
to bore is out if needed
have you checked to see what is wrong yet
take the drive off and try the motor again
good luck daren
hi bigdave has the same boat in an open bow and he took out the old 470 and installed a 305 chevy
we had a complete pakage out of another boat
the v-8 is real heavy in the back
good for wake boards bad for slalom skiers
I have an eluder with the 4-bbl version of the 470 at 190 hp
i run about 53 or so and pull skiers good
you can still get a reman short block from merc if you go that route
this is a wet sleve aluminun block and you would have to have the right equipment
to bore is out if needed
have you checked to see what is wrong yet
take the drive off and try the motor again
good luck daren
daren34
Member
engine
sorry i did not see the pics
let us know what you find
big dave took his apart and the sleeves were coroded at the top from running salt water through it
http://www.breezeworks.net/
this guy has a lot of parts for theese old motors and a lot of knowledge
good luk daren
sorry i did not see the pics
let us know what you find
big dave took his apart and the sleeves were coroded at the top from running salt water through it
http://www.breezeworks.net/
this guy has a lot of parts for theese old motors and a lot of knowledge
good luk daren
thanks alot for the info. and no i do not know what the problem yet im picking up the boat next weekend i will keep you updated this will be my winter project i use to build powerboats for intrepid powerboat in florida mainly gelcoating , fiberglass work type, and custon paniting. wish i got into the motor work end
fjowtlawrose
New member
I would put a4.3 v6 in it the important info you left out is what year is this boat. if you go biger your drive gear ratio will be wrong that 3.7 has a 1.85 to 1 gear set a 350 is a 1.50 to 1 and the 4.3 is 1.65 to 1. if you droped a4.3 in it ( I would at 300 hp built ) it would not perform well with the stock gears . I would find a used upper secton with the 1.50 to 1 . You will need the iner gible housing and a complete 4.3 4bbl carb engine carb to motor mounts . You will neen to modafythe stringers in your boat to mount a v block. A stock carbed 350 is only 260 hp and heavy a stock 4.3 with a cam head work and intake will make 300 hp on pump gas. or you could get fancy a friend i work with has a buick grand national with a turbo 4.3 making 800 hp on 93 pump fuel wiyh alcohol injection to cool the air charge to protect the pistons
fjowtlawrose
New member
I would put a4.3 v6 in it the important info you left out is what year is this boat. if you go biger your drive gear ratio will be wrong that 3.7 has a 1.85 to 1 gear set a 350 is a 1.50 to 1 and the 4.3 is 1.65 to 1. if you droped a4.3 in it ( I would at 300 hp built ) it would not perform well with the stock gears . I would find a used upper secton with the 1.50 to 1 . You will need the iner gible housing and a complete 4.3 4bbl carb engine carb to motor mounts . You will neen to modafythe stringers in your boat to mount a v block. A stock carbed 350 is only 260 hp and heavy a stock 4.3 with a cam head work and intake will make 300 hp on pump gas. or you could get fancy a friend i work with has a buick grand national with a turbo 4.3 making 800 hp on 93 pump fuel wiyh alcohol injection to cool the air charge to protect the pistons
Big Dave
Member
V8 POWER!!!
I took mine out for the first time since Memorial Day!
Oldest son trashed the 305.
JUst put a 350 into the Diplomat (same boat just open bow) in place of the 305
Mine came with the 170 mercruiser just like yours. the engine ran, but would blow water back out the radiator cap. Cyl liners were eaten upfrom the outside in. If you look, there are no stringers on the side of the engine bay, just boxes for foam. there is no structural integrity to the boxes, it is just 1/4 plywood to hold the foam. We took the boxes out completely, and custom built stringers from 4x12 oak stock and glued and glassed them into place.
also had to change the drive to 1.50 to one.
With the 305 4bbl, It would pull a 14 1/2 x 20 MACH STERNDRIVER to 4800 rpm(sorry, no gps or spedo)
I guess the carb got turned upside down while the engine was out of the boat for 3 MONTHS so did not have a good run with the new 350. oh my G@D, you should hear that 350 idle!!!!
Had 3in aluminum pipe bent by local muffler shop, and drilled 2 3in holes in the back for exhaust. (sealed them just like they used to do the old wood boats)
I took mine out for the first time since Memorial Day!
Oldest son trashed the 305.
JUst put a 350 into the Diplomat (same boat just open bow) in place of the 305
Mine came with the 170 mercruiser just like yours. the engine ran, but would blow water back out the radiator cap. Cyl liners were eaten upfrom the outside in. If you look, there are no stringers on the side of the engine bay, just boxes for foam. there is no structural integrity to the boxes, it is just 1/4 plywood to hold the foam. We took the boxes out completely, and custom built stringers from 4x12 oak stock and glued and glassed them into place.
also had to change the drive to 1.50 to one.
With the 305 4bbl, It would pull a 14 1/2 x 20 MACH STERNDRIVER to 4800 rpm(sorry, no gps or spedo)
I guess the carb got turned upside down while the engine was out of the boat for 3 MONTHS so did not have a good run with the new 350. oh my G@D, you should hear that 350 idle!!!!
Had 3in aluminum pipe bent by local muffler shop, and drilled 2 3in holes in the back for exhaust. (sealed them just like they used to do the old wood boats)
Big Dave
Member
v6
by the way, you would have to do the same work to install a v-6 as a v-8, and would only save 100lbs on the complete package.
The inner transom plate and gimbal housing are the same for all 3.7l engines as the one that would come with a v-6 or v-8 only the 3.0 4cyl has anything smaller.
Nothing sound better than a good small block with too much cam thru 2 3 inch pipes that cannot be 2 ft long
by the way, you would have to do the same work to install a v-6 as a v-8, and would only save 100lbs on the complete package.
The inner transom plate and gimbal housing are the same for all 3.7l engines as the one that would come with a v-6 or v-8 only the 3.0 4cyl has anything smaller.
Nothing sound better than a good small block with too much cam thru 2 3 inch pipes that cannot be 2 ft long
Adam L.
Member
My uncle has a 1990 sportfire I/O with the 4.3 V6 205hp. He has a land and sea transom jack attached to the alpha drive and runs a torque shift prop. The boat runs mid 60's. I always thought a V8 would sink that boat but I guess its possible. The new 4.3 V6s put out 220hp. You can get a new 5.0 merc that puts out 260hp.
cooperider
Well-known member
I saw that boat on ebay, and said something on here about staying away from it UNLESS you need the parts or want a project.
Looks like you got it at a decent price. I would do like has already been mentioned. Pull the motor and drives and upgrade to something more usable.
Looks like you got it at a decent price. I would do like has already been mentioned. Pull the motor and drives and upgrade to something more usable.
daren34
Member
4.3
the motor in the buick is a 3.8 and the bigger motor from buick performance is an uncut 4.1 litre with an uncut crank you have to machine all the parts
some might have bored and stroked a 4.1 to get 4.3 but the are not even close to the same motor that chevy has
the chevy even fuel injected marine is only around 220 horse power
i worked for a very large buick dealership in houston when they were producing the sfi 3.8 turbo regals and my dad was g.m. of the dealership and he had one for a demo
i was a mechanic at the time and went to 27 g.m. training classes and was certified on these cars and all the efi systems of the day
i am not trying to start any thing i just want the facts straight
the 4.3 chevy is a good replacement for the 3.7 but a lot of work is going to be needed
the foam boxes that are there are not stringers
they will have to be removed and real stringers installed before you can set for mounts
the drive if it is ok would still work you would just have to run a higher pitch prop
they recomend a 1.65 with the v-6
the 3.7 comes with a 1.84 or 1.98 high altitude
if the drive is good it will probably cheaper to find another 3.7 to go bak in its place unless you want to faster than 50 or 55
good luck deciding what to do
i have had good luck running mine with the 3.7 and its a foot and a half longer than yours
pulls slkiers good and gets better fuel economy than the v-6 or the v-8
good luck daren
fjowtlawrose said:
the motor in the buick is a 3.8 and the bigger motor from buick performance is an uncut 4.1 litre with an uncut crank you have to machine all the parts
some might have bored and stroked a 4.1 to get 4.3 but the are not even close to the same motor that chevy has
the chevy even fuel injected marine is only around 220 horse power
i worked for a very large buick dealership in houston when they were producing the sfi 3.8 turbo regals and my dad was g.m. of the dealership and he had one for a demo
i was a mechanic at the time and went to 27 g.m. training classes and was certified on these cars and all the efi systems of the day
i am not trying to start any thing i just want the facts straight
the 4.3 chevy is a good replacement for the 3.7 but a lot of work is going to be needed
the foam boxes that are there are not stringers
they will have to be removed and real stringers installed before you can set for mounts
the drive if it is ok would still work you would just have to run a higher pitch prop
they recomend a 1.65 with the v-6
the 3.7 comes with a 1.84 or 1.98 high altitude
if the drive is good it will probably cheaper to find another 3.7 to go bak in its place unless you want to faster than 50 or 55
good luck deciding what to do
i have had good luck running mine with the 3.7 and its a foot and a half longer than yours
pulls slkiers good and gets better fuel economy than the v-6 or the v-8
good luck daren