Mercury 7.5 just found one at the back of the garage

[Alicatt]

First post here, been away from the sea for a long time but my family have had a long association with the sea and boats/ships.

My younger brother passed away a few years ago, he was a radio officer latterly on an oil rig but when ashore he loved to fish and he had bought a Honda 4hp 4stroke outboard which I always knew was in the garage, however this week I have been clearing out the garage and found this Mercury 7.5 which the SNo. Plate says was made in Belgium. As I live abroad most of the time I had not got round to clearing out his "stuff" and after 10 years thought it about time

Anyway I have just hauled the engine out and thrown a bucket of water over it and washed it down, it has been well greased up and everything is corrosion free and all that should move does including a tentative pull on the starter to see if the engine was free and it turned over as one would expect.

I know nothing about Mercury engines being a long time user of a Johnson 85 ( military version of the 75 V4 2stroke) but not having used one in nearly 30 years, so I'm looking for any info or guidance about this little 7.5


Pic to follow...

 

[CLB]

What guidance are you after? Value? I would say it's probably worth £300 ish, give or take, as long as it runs. As a non runner, maybe £100 spares or repair.

If you are thinking about using it. Then they are generally good engines. Looks like a long shaft, so no good as a dinghy motor, but very useful as a yacht or motorboat auxiliary.

 

[Alicatt]

Thanks for that info, all I am really looking for is some general info about it, eg. Fuel/ oil ratio etc. Would I be right in thinking around a 50:1 ratio?

My step-son has expressed an interest in it so I'm taking it back to Belgium for him as he has been planning on getting a small boat of some sort. I have not tried to start it yet and will probably strip the carb off and clean it and the sparkplugs out before attempting. Pulling the rope it turns freely and there is compression. Once I figured out how to get the lid off it looks brand new inside, it has been well preserved with plenty of grease in all the right places.

There is a label inside saying it came from Moray Boat Center and checking the serial number it is from around 1980/81.

 

[Normalfornorfolk]

Personally I'd leave the carb well alone unless it shows signs of misbehaving, best not to fix what ain't broke. Plugs, yes, give them a clean and gap check. Fuel mix - doesn't google know? On an engine of that age it would be worth changing the leg oil if you decide to keep it.

 

[jfm]

Yes it is 80/81 from those decals. Nice engine. 50-1 fuel - oil mix for sure. Happy with 95 octane unleaded. I'd expect the spark plugs to be annular ring type, so no gap to adjust. Just wipe with rag.

I'd put some 2T oil in the bores and "run" it with no plugs, just to free everything up. And as stated above, change the lower gearbox unit oil ( which must be done right- needs an air pocket, don't absolutely fill it).

 

[Alicatt]

Thanks, will certainly pull the plugs out and give them a clean, then a spot of oil down the bores, carb did look ok as I looked down the choke bore and it moved freely.

Just now we are about an hour out of Ijmuden on a limping ferry with only 3 of it's 4 main engines running