New to mercs - what exactly do I have here?

[JoshKeller]

Hey guys, took a boat on a trade and it has a merc/mariner motor on it. Serial number for transom bracket is 6637220 - 150 hp.

The intake manifold has the number 969-9078-c1. The heads are 18787-c2 for both. Carburetors are wh-39-1,2,3 with the top and bottom being 1626 and the middle 1346.

What exactly do I have here? Is it a 2.0, 2.4, 2.5 block? Is this thing safe to run with the jumble assortment of parts? Approx year and true horsepower? Thanks so much!

https://i.ibb.co/nCsbrw5/20191019-185230.jpg (https://ibb.co/Ryp92gV)

https://i.ibb.co/n61wb9h/20191019-183729.jpg (https://ibb.co/17X0L1H)

https://i.ibb.co/Kx6RCkL/20191019-183737.jpg (https://ibb.co/23qmXQs)

[gotboostedvr6]

Old 2.0

They are good motors.

[JoshKeller]

If it has been bored over before, will the pistons be stamped with the oversize amount?

[JoshKeller]

To add - not sure if its pertinent info, but the bore on all 6 is 3.375" +/- .001 according to my digital caliper

[gotboostedvr6]

Mercury Piston Standard 2.0L Bore Size is 3.125

[gotboostedvr6]

Mercury Piston Standard 2.5L Bore Size is 3.5"

[gotboostedvr6]

Mercury Piston Standard 2.4L Bore Size is 3.377

[gotboostedvr6]

Take several pictures of the intake manifold behind the carbs.

Also put a magnet on the cylinder and see if it sticks.

[JoshKeller]

All 6 are 3.375" and a magnet does not stick.

[JoshKeller]

https://i.ibb.co/NZRT5M1/20191020-135507.jpg (https://ibb.co/r49dYVb)

https://i.ibb.co/w0KpZmm/20191020-135515.jpg (https://ibb.co/smFspYY)

[gotboostedvr6]

It's a 2.4 liter 175 or 200hp with late model one peice heads.

[vnemous]

1985 2.0 150 ELPTO sold in 1987 per serial number given:D

[JoshKeller]

1985 2.0 150 ELPTO sold in 1987 per serial number given:D

Is that off the motor bracket serial or off the powerhead?

[vnemous]

6637220 Even starter has manufacture date on 1985

[Merc 2.5]

All 6 are 3.375" and a magnet does not stick.

I'd say chrome bore 200. It has 200 on welch plug. I had 2 ,2.4 200 with that 200 on plug,, also the air box is fir 200 also , the 150 had diff air box
But then again a vertical 150 clam shell wont fit horiz 200 without mods. Does it have turnbuckle latches? Or 1 big one in front?

[JoshKeller]

It has two turnbuckle latches

[Merc 2.5]

It has two turnbuckle latches

Gotcha. Well since I dont trust tha tag on mid (get swapped around alot) and 200 on block with no numbers. U mite had got reman powrrhead to. Really need find #s on block and c if match the mid tag

[Merc 2.5]

Let me ask u this. When cowl is on mota does it have the front cover also or is it missin or wont fit? Maybe take a pic of front of cowl

[JoshKeller]

Let me ask u this. When cowl is on mota does it have the front cover also or is it missin or wont fit? Maybe take a pic of front of cowl

It has the center piece, but it doesnt really fit at all. In fact, it was laying in a rod locker in the boat.

The Reman powerhead is what I was told was put on, but they never said it was a 200. Just the freeze plug is stamped 200, and it seems that the intake manifold has a 200 part number, so do the carbs. The bore seems to be 2.4 liter as well.

[Merc 2.5]

U got a chrome 200

[Merc 2.5]

Front piece wont fit over that air box. that's y I asked

[JoshKeller]

U got a chrome 200

Good motor? Is it a true 200 hp? Is that a 2.4 liter? Does the chrome bore require special pistons/rings/etc? Anything especially important to know about it?

[Merc 2.5]

Nothin special bout it but yes very gud strong 2.4. Just cant port it unless u get rechromed or sleeved. Just do normal mods. Uses different ring than steel sleeve , same pistons u got a good sleeper under 150 cowl lol

[Merc 2.5]

If I were u I'd pull powerhead and see if exhaust ports on bottom block match ports in adapter plates and see if it has the real long tuner still?

[JoshKeller]

Nothin special bout it but yes very gud strong 2.4. Just cant port it unless u get rechromed or sleeved. Just do normal mods. Uses different ring than steel sleeve , same pistons u got a good sleeper under 150 cowl lol

Not really interested in doing any mods - just want a good reliable motor for my bass boat. Boats rated for 200. So dont want to go much more than that. Will be pulling the powerhead to rering the motor so its fresh. Will check the adapter plate and tuner then. Unfortunately theres no prop, so I'll have to do some research on where to start. How many rpm should I shoot for wot?

[Merc 2.5]

6k. If it runs gud and no mods and cools good just run it

[JoshKeller]

Any suggestions on a prop to start with on a 1200 lb pad bass boat style hull?

[Merc 2.5]

Tempest or trophy. Start with 24 on trophy or maybe 25 or 26 tempest. U got a jackplate?

[JoshKeller]

Tempest or trophy. Start with 24 on trophy or maybe 25 or 26 tempest. U got a jackplate?

No jackplate. Really not worried about speed, just want motor longevity. My current boat is an outboard jet that does approx 35 mph, so I'm happy with whatever I get, so long as the motor lives a happy life.

Holeshot is my priority. We fish some rough lakes and getting on top of the waves fast and staying above them with less than full throttle is what I need

[Merc 2.5]

Trophy 24 or 25 all day. 5800 6000 u good

[JoshKeller]

Since this is a 150 mid/lower does it having 2:1 gearing change prop selection any?

[nitro_rat]

Just saw this but from your photos it's definitely a 2.4 200. Merc2.5, you can see the side of the airbox in one of the first pics.

JoshKeller, did you count the revs of the propshaft to driveshaft to determine if it's really a 2:1 lower?


Since this is a 150 mid/lower does it having 2:1 gearing change prop selection any?

One pitch. 24 pitch on a 1.87 is roughly equal to a 26 on a 2:1.

[Merc 2.5]

Just saw this but from your photos it's definitely a 2.4 200. Merc2.5, you can see the side of the airbox in one of the first pics.

JoshKeller, did you count the revs of the propshaft to driveshaft to determine if it's really a 2:1 lower?



One pitch. 24 pitch on a 1.87 is roughly equal to a 26 on a 2:1.

Yep I seen that

[JoshKeller]

I have a buddy willing to give me a 24 trophy 4 blade. Good choice? He has none of the plugs - should I get the solid plugs, small hole, medium?

[JoshKeller]

Upon further review I believe it has 1.87 gears in it. Marked flywheel and prop shaft at 12 o clock. Turned flywheel one whole revolution. Prop mark was at 11 o'clock after. A little hard to see the mark, it's in the beam of sun

https://i.ibb.co/tXp0tnR/20191023-154616.jpg (https://ibb.co/jRkC2qt)

[Merc 2.5]

Yes 1.87. And 24 great 1st choice to (try) mite need get it pitched up to 25 or 26. But ur 24 can got up to a 26 with work

[JoshKeller]

Yes 1.87. And 24 great 1st choice to (try) mite need get it pitched up to 25 or 26. But ur 24 can got up to a 26 with work

Great. Thanks. What plugs would be good to start with?

[Merc 2.5]

Buhw ngk

[JoshKeller]

Buhw ngk

I meant in the prop. Looks like they have full plugs, small hole plugs and medium holes

[Merc 2.5]

Start with all in and start pullin 1 plug at a time until u like the slip and hole shot , start gauging that way
Should b fune this way to get a round about of what u need