1976 50ph 500 verses 1971 85ph 850 ???

[Lost Fisherman 1976]

I have just finished the hull of my 1976 Magnum and have a Question that the Pros will have a lot more insight than I.

I need to rebuild but which outboard do I go with,

The original outboard on her is the 76 Merc 500 50 s#4361149 ran her around 31mph 5000 rpm. Number 4 lost 40 psi, she needs rebuilding!

The Coast Guard Tag rates her at 85hp.

I have found a 71 Merc 850 85hp s#3745415. I can get from a old trust worthy friend that said the motor run strong 6 years ago went last ran. A little oil and 6 turns with the rope gave me pressure around 120psi per cylinder. All he wants for it is for me to get it out of his barn. A hard day of work cutting, recycling, and a landfill trip. (cheap!)
Which would you rebuild?
What are your thoughts,the pros and cons of the above outboards?
Thanks Pros!

 

[Faztbullet]

Re: 1976 50ph 500 verses 1971 85ph 850 ???

I would go with the 850 as when you go to rating hp at the the prop the 850 is about 75 hp and the 50 is about 42hp.

 

[dwco5051]

Re: 1976 50ph 500 verses 1971 85ph 850 ???

I would go for the 850. The price is right. I have done that much work in a day for neighbors for a couple of cups of coffee and a few loaves of home baked bread

Clean up the 850, try it on the water and see how it runs. If it runs good spend the winter rebuilding the 50 for a spare.

If they both need a lot of work then the question comes up of which one to invest time and money in. More power or better ignition technology and less fiddling around to keep running.

 

[Lost Fisherman 1976]

Re: 1976 50ph 500 verses 1971 85ph 850 ???

That's what I was thinking as well. Clean-up the 850 get her running and switch out. Rebuild the 500 in the winter cold.
I just wanted to make sure there were no wise-tells about the 850.
Something I didn't want to hear after I mount it on my boat.
Thanks guy's!

 

[Chris1956]

Re: 1976 50ph 500 verses 1971 85ph 850 ???

The only negatives on that 850 is that the wiring will likely be brittle and w/o insulation, and the distributor-based ignition works great, but when it breaks, it is pricy to repair. I would tape up the motor wiring harness, and test her for spark. If she has it, get a new wiring harness.