TOPIC: mercury 115 any good?

Is a mercury 115 power tower a good motor? Anything I should look out for?

There are (4) distinctively difference 115 Towers of Power.
The '70-'73, the '74- early '79, the late '79-'80, and '81-'88.
IMHO,...The two most desirable models would be the '70-'73 which can be easily modified to the specs and performance of a 1350.
The '81-'88 which had power-port pistons, alternator driven ignition, and were as close to the earlier model 1500 as you can get. Low dome pistons - vs - the earlier and more problematic high dome pistons of the 1500, but with internal tweaks of the reed stops and fatter carburetor main jets, and its alternator driven ignition with no rev limiter - the late 115 could become a real monster T of P.
The 'nut shell' version.
doc F

The motor i'm looking at has the hei ignition system which would be one of the less desirable models correct? It also needs rewired, i'm not sure why yet.

I'm also looking at a 950 that needs a lower unit. If i'm correct that one is a 1966 or 1967.

and an 850

Which one would be my best bet Doc?

You'd be far better off going with the more "modern" 115 than a mid-60's 95 hp.

The main thing you'd need to be concerned with on an older motor is condition.

If the 115 has good compression and is not a "Salty Dog", it'll be very repairable. Plus it's a much-improved design over a 60's motor.

Most likely the wiring issue comes from deteriorated wires. The wiring harness can be replaced (or repaired if possible). New wiring harnesses are typically less than $200. Electronic parts (distributors, switchboxes, stators, etc) can be very expensive so it would be good to know the specific problem. There's a huge price difference between any running motor and one you can't run to checkout, so don't pay Big Buck$$$ for what is essentially a "parts" motor.

If you're referring to an 850-4, it's a good motor but has issues with overcooling due to design. If it has been fished all its life and spent lots of time idling, likely the cylinders will be worn out. I'd recommend a leakdown test (not just a compression test) when buying one of those. Failing that, it needs to be run on the water to see if it starts, idles, throttles-up, and operates at speed like it should.

Some pics or more details might help us help you make a decision as to which motor is the best for you boat.

BTW, there's "desirable" and then there's "collectible"; some are both!

Doc works on a lot of classic collectible Mercs, but a later-model motor that's in good shape (or has the potential to be fixed) is certainly "desirable".

That being said, one of the coolest motors I ever had was a '71 1350-6 on a 16' Sidewinder SS, in the 80's. I transplanted that to a Seaswirl Spyder and sold the boat in the late 90's. My good boating buddy saw it last year and I guess it's still running good. Quite a motor! Many times I have regretted selling that one.
There's just something about a red-striped Merc!!!

HTH..........ed

Thanks for all that info. I will hold off till I can hear/see one run.

I sure hope the 115 is a good one, I just bought a 1977.
Great info here, thanks.

As far as engines go, that is one of the best. If the overall condition is good then you will not be disappointed. Grab a factory manual and have at it, and we are right here to help you through the rough bits.

I have been looking for a factory, not Clymer, shop manual but haven't had much luck. Anyone have a idea of a good place to get one? I have a 1977 115.

I have a '77 115 and have had good luck with it. I found a place online where I downloaded a factory manual for $5 if I remember right. I just print out the parts I need as I need them. It covers several years and sizes of motors. It is very detailed and has been useful. I am sorry, but I don't remember where I found it but I thought I would let you know they are out there.
Bill

Have you checked here for your manual?
boatinfo.no/lib/library.html#

Thanks Mark! That will be helpful but being a old gray haired goof that I am I still want a real book.

I'm the same way, but just thought I'd throw that out there in case you needed it before you could find the "hard copy" book.

They do come up on eBay once in a while, I always try to stay with the official factory books if possible.

Agreed, IMHO the aftermarket books are not worth much, if anything. Stick to the genuine article.