Old Mercury Identification

[mark weaver]

A fellow gave me this old Merc. He said he thought it was a mark 28. I think the cowl IS off a 28 but don’t think the it is that model. It does have that CLUTCH adjuster on the throttle linkage like the 28 but the numbers do not match a mark28 as far as I can find. Could this be a 60 or 61 200? It has ROCKET stamped on the powerhead below the fuel pump, not hurricane. This old motor sat outside for TWO winters in all kinds of weather…did a compression test dry… 115 and 114. sprayed some gas in the cylinders and 3rd pull going. Hooked up the gas line and sat there and idled. I have a 1958 mark 10 I am replacing the water pump in and the powerheads look A LOT ALIKE. Can anyone shed a little light on what this is? Does anyone know what that round adjustment with the 2 screws on springs does? Pics below.

[dave-bernard]

1961 merc 100 9.8hp with mark 28 top cowl.

[mark weaver]

Ok, I thought she was small…just about the same as my 58 mark 10 with a few differences on the engine.

[mark weaver]

I just looked on YouTube at the 61 9.8….not the same. Mine has the white button on the end of the tiller handle that you are supposed to press to go to neutral or reverse. It also has the cover in front of the leg where the automatic reverse and forward springs are. So it is the same pain in the A…to change the impeller as the Mark 10 I am doing now.

[billw]

There was a later, white model (I think 11 cubic inch and much smaller) that was 9.8 hp too, but I think that’s when they changed the designation to “110,” instead of “100.” Dave could be right because I think the last rendition of the Merc 100 auto tranny WAS in fact, designated 9.8 hp. Questions: What does it say to the left of the serial number? That’s where the model number should be, at least for the midsection. Now I might be wrong but I looked at THREE of my Merc 150s and the power heads all say “rocket” on the starboard side. I believe the 100s say the same thing. So in my mind, if you’re lucky, it could be a 150, too, unless I am missing something. What’s the carb number” That might help, depending on what year. (The 150 had four reeds per cylinder.)

Long live American manufacturing!

• This reply was modified 1 year, 2 months ago by billw.

[mark weaver]

Here is three more pics. There is nothing left of the serial number. The carb is a tillotson KB4A fixed high speed jet. I am looking on oldmercs site and max rules and acording to them sites 1452097 it can only be a 9.8 or a 200. It has a smaller prop than my 58 mark 10 but it has that clutch adjustment on the throttle mechanism that my 58 does not have. WHAT is that 2 screw clutch rig for?? No idea what that is and can’t find a thing on that.

[mark weaver]

I can’t even find an outboard with that exact ID plate with the stripes on it like in my pic….not a mark 28 or mark 10 or 200 or 9.8 of ANY year…. none of them have that.

[billw]

KB4A is consistent with a Merc 100.

Long live American manufacturing!

[mark weaver]

That must be what it is. I don’t know why it has an ID plate that I can’t find anywhere and it is VERY heavy for a 100. Thank you Bill and Dave for your help. I need to tackle the water pump impeller after my Mark 10 is done, I have it all apart and waiting for an original impeller not a sierra 18-3008 with the round key slot.

• This reply was modified 1 year, 2 months ago by mark weaver.

[billw]

I have a couple of 1962 Merc 250s with that type of ID plate. 1962 was the last year for automatics and only the 250 model was offered that year. It makes total sense that yours is a 1961 100.

The pumps in the Merc series are a little tiny bit easier to do than the Mark 10; but not much.

Long live American manufacturing!

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