Mercury 7.5 HP Motor Refresh (1969 model year)

[tpenfield]

Sunday update . . .

I decided that the wobbly trash barrel was not such a good thing to be running the motor in, so I decided to build a motor stand. Three 2x4's is all that it took.




I was wondering if the idle speed that I set yesterday was gong to be OK. I happened to find a manual of a newer 8 hp Merc that had a spec for the idle setting . . . 850 RPM in gear.

So, I ran the engine some more today (with motor stand) and checked the idle both in neutral and in gear. Neutral is about 1100-1200 as I had posted yesterday, and in gear it is about 900 RPM. So, it should be fine. :thumb:



The engine seems to be running very well, but I won't be able to give it a full testing until boating season begins . . . still about 3 months away.

I do need to clean the motor up and apply a final coat of paint, then add the new set of decals.

 

[racerone]

If tachometer is correct the speeds are too high !

 

[tpenfield]

it is an old tachometer, but I believe it is still accurate. What should the idle speed be on this motor?

 

[merc850]

I'd bump it down to 700 in gear to lessen the shock on the shift clutch.

 

[tpenfield]

I'd bump it down to 700 in gear to lessen the shock on the shift clutch.

OK, thanks. I have not been able to find a specification for the idle speed on this vintage of motor. Any info in that regard?

 

[60sboater]

I see 650 in forward after warm-up....Source Seloc 1404 manual...65-89 2 to 40 hp engines. This is for the carb used on a 69 7.5 hp,among others.

 

[tpenfield]

Thanks for the info on the idle setting. 650 RPM seems pretty low, but I'll see what I can do.

I did the final coat of paint and put on the new decals. So, it is all spiffed up for the coming boating season.









I'll probably wait for some warmer weather or even the beginning of the boating season to set the idle.

 

[60sboater]

Looks great...like brand new.

 

[tpenfield]

Looks great...like brand new.

Thank you. Hopefully it runs well. It is coming up on 50 years old, I've owned it for about 4 years.

I've done a few things to this motor in that time.

Previously:
Replaced the wiring harness (DIY)
Replaced the ignition cutoff switch
New fuel fitting, fuel tank, and fuel line.
New lower unit seals
Stainless steel drive shaft (from a 1980 motor)
Anodes on ventilation plate (Clamshell style)

On this rebuild:
Added a second grease fitting at the lower end of the steering pivot
New gaskets
New crankshaft bearings
New piston rings
Re-painting
New decals

Hopefully, I'll get some more years out of it until I can scrounge enough $$$$ between the sofa cushions and elsewhere to buy a new one

 

[tpenfield]

Here are a before and after pic. . .

Before After​

 

[tpenfield]

Of course, I just noticed from the 2 pictures that I put the "Mercury" decals on the opposite way from the originals :facepalm:

Oh well . . .

 

[GA_Boater]

The new decals look blown back like she's up to speed sitting still. Gonna add to the top speed.

If you hadn't pointed that out, no one would know. Mums the word, we won't tell. :tape:


She does look good all dressed up, Ted. Super job!

 

[tpenfield]

Thanks. Yes, the decals swept back should make the engine go faster :thumb: . . . or at least look like it is going faster.

I was hoping that I would not have to start over because of the decals

 

[GA_Boater]

The tricky things will go faster the 2nd time - Hopefully. :smile:

 

[tpenfield]

I ran the engine again and set the idle speed down a bit. I got the in gear speed to be in the 700 RPM range, but it basically varied from 600-800. I had to tweak the fuel mixture to get the engine to stay running at that speed, but it does stay running consistently. So, looks like it is all good :thumb:

 

[60sboater]

congrats

 

[GA_Boater]

Now I see how you can tilt the motor and pull the stand away from the barrel. It would be tough with the round barrel in the earlier pics.

Are you doing a Dawn flush or brewing beer? LOL

 

[tpenfield]

congrats

Thanks for your help along the way :thumb:

 

[tpenfield]

Now I see how you can tilt the motor and pull the stand away from the barrel. It would be tough with the round barrel in the earlier pics.

Are you doing a Dawn flush or brewing beer? LOL

The round barrel does not seem to work out as well with the motor at the slightly raised height due to the casters now added to the stand. I can still use the round barrel, if I want to fill it to the top. With it being winter, I have to do a bucket brigade from the kitchen sink to fill the tub/barrel. The motor can be pulled away from the round barrel, if I tilt the motor while pulling the stand away.

I do like the shallow 'tub' though . . . seems to handle the prop wash better than the round barrel.

Brewing beer with an outboard motor . . . now that's something that would have a unique taste to it. I usually run some dish soap to break up the spent oil.

 

[GA_Boater]

I tore up an newish impeller running in a barrel over a several week period while working on a problem. Didn't drain the barrel, kept it full. All I can think of is the oil build up caused the rubber to fall apart. Dawn might have broken down the 2 stroke oil. Gotta keep that in mind for next time.

Ted's Summer Dark. Mmmm - Full bodied with a hint of sea air and Dino burps. :smile: