Engine detail request from England

[The Moosehunter]

Hi folks<br /><br />Another ID request to anyone who has access to the Mercury database.<br />I have just bought a motor serial number 9177806 (Belgium I believe) with the id "871-8337 marathon" on the cylinder head, and am after as much info about this as possible from anyone who has any knowledge of this motor. Especially any details on what sort of choke mechanism it should be fitted with, as it is a bit stubborn to get going in the cold.<br /><br />Many thanks from a cool UK<br /><br />Cheers<br /><br />Andy

 

[rickdb1boat]

Re: Engine detail request from England

Do you know the horsepower of this engine?

 

[The Moosehunter]

Re: Engine detail request from England

Sadly I do not. This is part of the info I require. I recently bought a 15ft Dateline speedboat with this mystery outboard on it. Somebody has repainted it black so there are no identifying marks on it at all. I have been told buy a helpful guy on the phone at a local service department that it sound like an old Blueband somewhere between 60 and 80 hp. It's a 4 cylinder model, and that's about all I know so far. I need to ID it so I can purchase a workshop manual and see if it's up to the job.<br /><br />Positive ID of this motor would be greatly appeciated.<br /><br />Cheers<br /><br />Andy

 

[rickdb1boat]

Re: Engine detail request from England

(80,0)HP 9177626 - 1978 4 cyl

 

[The Moosehunter]

Re: Engine detail request from England

Just to clarify the info you quoted, is this the nearest serial number to mine (9177806) available ? And does the (80,0)HP imply that this is indeed an 80hp motor ?<br />Sorry to sound a bit stupid but I'm new to this outboard lark.<br />Thanks

 

[rickdb1boat]

Re: Engine detail request from England

It is the nearest I can come without actually knowing the HP for sure. Unless it's a 50 HP, there are numbers that match that one also. The 4 cylinder helps narrow it down, but there are many alike numbers for Mercs. For example, the 50 HP goes like this50,0) 9136250 - 9195685 1977 4 cyl. The 60-75 HP has no match for a 4 cylinder, so I have to assume from the info you give, it's the 80 HP.

 

[The Moosehunter]

Re: Engine detail request from England

Thanks for the info Rick, this has helped narrow it down. From the look of the engine cover, I would say that it is bigger than a 50hp, however looks are sometimes deceiving, just ask the wife.<br />Is there a sure fire way of getting the missing info, such as marking on the engine casing that may identify cubic capacity or something ?<br />Appreciate your help.<br />Cheers

 

[tmcalavy]

Re: Engine detail request from England

Call the service guy again. Ask if there is a difference in stroke between the 50 hp and the 80 hp. Find out the stroke for each...such as (pure conjecture) 5.5 inches, etc. Now pull a spark plug, rotate the engine until a piston comes to the top of the bore. Insert a gauge (perhaps a stick/rod with inch increments marked on it) in the plug hole and let it rest against the piston. Rotate the flywheel and measure the stroke (distance from top of cylinder to bottom) as the piston moves. This should get you in the ballpark if there is indeed a difference in stroke between the 50 and the 80 hp motors.

 

[andrewkafp]

Re: Engine detail request from England

Moose<br /><br />I think you will find that the 4 cylinders have the same sized covers. So a 50hp and a 80hp would look the same. It's only when you go to the inline 6 that they get taller. The bore and stroke would most likely be the main difference.<br />Rick is usually pretty spot on, and if so it's likely to have and electric choke soloniod located above the top carb, with a linkage attached to both butterflies. It is normally activated by a black button on the controller or by pushing the key in. The butterflies must fully close for best results and you can check it by running a positive terminal to the "live" side thus by-passing the switch. You can also get an indication of age by whether it has a distributor or 4 coils. (Introduced in @1978)