help!!! i need to know what it is that my fater bought me??

alilley

Petty Officer 1st Class
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Jun 7, 2010
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327
I will start off by saying that this forum is a great tool for begginer (such as my self)right now to a seasoned veteran boater and the same for mechanic. I have learned alot from just readding post on here with both learning how to handle the boat and how to fix thing my self.

So here goes with the issues at hand here. i bought my first boat back in july. the boat hat a 3.0 mercruiser/alpha 1 out drive. when i purchased it i was informed that it had a cracked block. the price was right for it so i purchased with the hopes of it just being an external carck. Well i fixed that, got it on the water and she ran really good, i just felt that she was running about 500 rpm short at w o t. after changing the oil out on it twice with less the 5 hrs run itme on the fresh oil, and both times it coming out looking like a melted wendy's frosty i descided to pull the head off. After getting it off noticed a blown head gasket in 2 places, between cylender 1&2 then again 2&3. one of them is just a clean break so it could havehappened when pulling the head off. but the other one is ovious it was burned through (causing slight loss of power and lowered w o t r p m). After coming up with this information i stated to do some digging around trying to find a good used block (talk about a challenge).

the good news.-------dad callse me up today and tells me that he found me a used moter @ this scrap yard. it is a marine moter, and from he can tell the block is not busted. dad goes a head and buys said moter fopr 65$ and tells me to come and look at it. i get there look it over, dad has it tipped up side down so water dont drain into it. some oil had leaked out of the valve cover and it looks good (not like a frosy just dark and smells of gas and still had good thickness and not thinned out from water) i can tell by looking at it it is a g m marine moter and it is older then mine (mine is an 87) the block to me looks to be the same the (maybe bad) we tried to turn it over only by hand and it would not turn but this was by hand outside in the wind and cold so we didnt try very hard.

now for my questions----
what did dad buy me?
will it work for replacing my currrent motor?

for more information on the "new motor" please see attached photos. i have included photos of all 4 sides and of the casting numbers we did see a place where there was some number stamped on a flat spot of the block behind the fuel pump and distrubator and they are ------V09053cf----- i am assumin this a serial number???

sorry for the long post here just trying to giver as much detail and history about what is going on and many thanks in advance for all the help that i know i will get
 

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alilley

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Re: help!!! i need to know what it is that my fater bought me??

the other half of the casting numbers
 

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cr2k

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Mar 19, 2009
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Re: help!!! i need to know what it is that my fater bought me??

First off it is out of an OMC, but that doesn't mean it won't work. I hope someone will chime in here, but I believe it is a much older 120 engine.
 

fishrdan

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Jan 25, 2008
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6,989
Re: help!!! i need to know what it is that my fater bought me??

Odd looking manifold with the dual carbs. My guess would be a late 60's 120 or 140HP Mercruiser,,, or OMC. My 73 140HP Mercruiser looks a bit different (manifold, carbs, external regulator for the alternator?) but similar on the starboard side of the block. What color is the paint on the block, looks to be very oxidized blue, blue = OMC.

I'd be concerned if it's rusted up inside (locked up), if the block is usable and if it's a 140HP/3.0L/181CI, not a 120HP/2.5L/153CI.
 

alilley

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Messages
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Re: help!!! i need to know what it is that my fater bought me??

i believe my 3.0 is a 140 hp.

i forgot to mention that my 3.0 was a running motor till i pulled the head off. me and dad was talking, we figured that even if the "new motor" is siezed up as long as we can save the block then we coulg get a set of pistons and a set of rings (if the 3.0 wont fit it) then put my carnk in it. we would like to use as much of teh internals of my 3.0 as we can even if we have to have this new block bored to fit and kind of take 2 to make one kind of things or use the best of both worlds
 

Bondo

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Re: help!!! i need to know what it is that my fater bought me??

Ayuh,... You've got yerself an old OMC, 120hp 2.5l motor... I believe...

The 1 picture of the front is incomplete, 'n I can't see the front of the crank...
If it's Just a pulley it's a 120hp...
 

Howard Sterndrive

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Nov 5, 2008
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4,603
Re: help!!! i need to know what it is that my fater bought me??

that's a 110HP OMC 2.5L, 153 cu. in 4 cyl Chev
same motor as a 120HP, but rated less due to the dual 1V carbs.
The last year for those dual carbs was 1971, earliest was around 1966

The block will replace an 87 3.0 just fine, but you'll be shy 20HP with the smaller displacement motor
 

wallerus

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Jan 8, 2010
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Re: help!!! i need to know what it is that my fater bought me??

As far as I know, you cannot put a 3L head on a 2.5 due to wider valve spacing on the 3.0. I would continue looking.
 

alilley

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Re: help!!! i need to know what it is that my fater bought me??

ok so it sounds like it is not the right motor but it si close. we have not tore into it yet. just courious if any one can give me some specs on this o m c motor? looking ofr stuff like bore, stroke, what about craink jernal sizes? here is the idea that i currently have

strip my 3.0 of all the internal rotating parts, strip this o m c of all internal parts. take all the parts (old 3.0 block crank rods pistons and the omc block) up to my local machine shop and have block bored to fit my mercruiser parts since mine are still in really good shape.---i got to doing some reasearch on doing this at one time and found out the the mid 80's modle 2.5 had the same crank jernal sizes as the 3.0 even used the same thrust bearing. if i went this route i would prob reuse the omc head since i was just informed that the 3.0 head wont fit but would my maniflod fit the omc head. i know from dealing with machine shops in the past that not only can they bore cylender walls but they can line bore the crank jernals

any one got any thoughts on doing this?? or should i continue looking for a 3.0??
 

Bondo

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Re: help!!! i need to know what it is that my fater bought me??

any one got any thoughts on doing this?? or should i continue looking for a 3.0??

Ayuh,... The difference in Bore is to great, ya Can't over bore a 2.5l to a 3.0l...
 

alilley

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Re: help!!! i need to know what it is that my fater bought me??

might not be able to bore a 2.5 out to equil the same displacement as a 3.0 but you do not get all your displacement from just the bore correct me if i am wrong but displacement is bore x stroke x number of cylenders. and if i did the math correct and if the numbers i got are correct then with the bore of a 2.5 and the strok of the 3.0 would still come up eith the same displacement. if i read correctly in a differant forum that this 153 omc will use the same cam shaft as the 3.0? so what i am thinking there is if the bore is even close tehn a slight over bore and putmy 3.0 crank in the 153 omc i should come close to the same hp as what i have now?? i would have to use teh 2.5 head and if it would fit i would rather use my 3.0 intake but if i had to as long a i can the the risers and stuff to make it would then i would use the 2.5 manifold any body think this will work?? has any one ever done this before? in theory it is the same as putting a 400 crank in a 350 and getting a lot more torque and hp then you would using a 350 ( i am not after more hp or torque just trying to get my boat back on the water)
 

dan t.

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Re: help!!! i need to know what it is that my fater bought me??

Probably wrong wrist pin to piston deck distance. Pin hight is matched to stroke
 

alilley

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Re: help!!! i need to know what it is that my fater bought me??

does any one know where i can fine the specks like that at? so i can look this this stuff up who i can get a hold of to check it out? i live in a central illinois and do have a reputable regrind shop in my town whould they have the info i need? or would i need to get a hold of regular engine rebuilder that we have in town? the engine rebuilder does do boring, line boring and all that what not and teh regrind works with cranks, cams, and rod mainly? who should i talk to for this??
 

Bondo

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Re: help!!! i need to know what it is that my fater bought me??

who should i talk to for this??

Ayuh,... I'd think either of the Shops should have a grasp on it...

Factory Manuals would list the specs...
 

proshadetree

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Jul 19, 2008
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1,887
Re: help!!! i need to know what it is that my fater bought me??

My opinion You will not be down much on HP build the engine using all the parts that will fit off of your old motor. Really in a boat 20 HP is not much to give up on an inboard. I have cammed and stroked a 350 with dismal results. In a car this engine would break your neck in a boat not so much. It takes large hp numbers in a marine application to even notice a difference.
 

alilley

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327
Re: help!!! i need to know what it is that my fater bought me??

does any body know if the 3.o maifold will work on the 2.5?? i wouyld much rather reuse that manifold and carb set up (carb was just rebuilt) then the one that is on the omc plus the chances of finding parts for the single barrel carbs is going to be yet another chore
 

alilley

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Re: help!!! i need to know what it is that my fater bought me??

let keep in kmind here that i am not tryingt o get a huge differance on the hp all that i am trying to do here is keep or maintain what i currently have as i have been informed before that this boat is border line under powered (boat is a 17 ft fiber glass tri hull deck style)
 

Bondo

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Re: help!!! i need to know what it is that my fater bought me??

does any body know if the 3.o maifold will work on the 2.5??

Ayuh,... Sure will...

Use Everything off the 3.0l on the 2.5l,.... Everything...
 

alilley

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Re: help!!! i need to know what it is that my fater bought me??

ok i have done some reasearch on both motorsand i will post what i have found. i only have one question i have read some where in a differant forum that both the 3.0 and the 153 cid ran the same cam. can any one confurm that?? this is the link to where i got my info from

http://en.wikipedia.org/wiki/Chevrolet_153_4-cylinder_engine

----bore----
181 cid-----4.00
153 cid-----3.875

----stroke----
181 cid---3.6
153 cid---3.25

i would not need to be concerned about the rod jernal sizes cus i would be using my 181 rods (as long as they are not to long) if i have to use the 2.5 rods and pistons i should not loose hardy any power as the diplacement loss would be minumal. if i need to clearance the block that should not be to much and nothing that a die grinder cant take care of. any opne else think this is going to work for me yet????
 

CharlieB

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Apr 10, 2007
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5,617
Re: help!!! i need to know what it is that my fater bought me??

Your biggest problem will be finding the correct pistons to use.

Stoking any motor requires the new pistons not only fit your bore size, but the piston pin height must be correct or the piston will set either too high or too low in the block at TDC.

Yes you have two sets of rods to chose from, either set will function, but each set requires the correct piston for that rod length.

You may end up ordering pistons, which could be a costly endeavor.

Do lots more homework before you start buying any parts or having any machine work done.
 
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