1977 Mercury 1500 performance?

Johnsonboat · #1 02-16-2014, 05:36 PM

I'm going back and forth on what to do to put a motor on my boat. I have a 1977 1500 20". I will have to put an extention kit to 25".
I'm going to find out tomorrow what that will cost.
I wondering if anyone has had this motor on a center console v? At 301lbs. I would assume power to weight would push the boat but not sure. And how do you like it?
It would be a cool novelty since the boat is a '77 also as long as it runs good.

This would only be for a year or so, then I will have money"I hope" to put a newer motor on.
The motor was free and the boat cost 400 so im not doin too bad with the basics of this project.
Maybe another dumb idea but worth a shot. I appreciate your thoughts. Sorry im all over the place on my posts but im new to this internet chat cult stuff.

smokeonthewater · #2 02-16-2014, 06:33 PM

I have a '76 merc 1150 on my V-20 CC and it pushes her very well.... planes almost instantly with IIRC a 15 pitch prop.... I don't have a top speed number for ya though..

Before you spend a penny on digging up a 35 year old used shaft extension kit, look HARD at the wiring harness on the motor.... they rot and aren't cheap... ALSO look at the wires coming out of the stator... they rot too and then require a new stator... also not cheap.... while you are at it before you run that engine do a compression test, go through the carbs, and DEFINITELY do a link n synch.

If she's healthy now you have a great old engine but neglect the last two steps and it can become scrap metal FAST

after that install a new diaphragm kit in the fuel pump and a new impeller in the lower unit.

ALSO replace the fuel hoses on the engine.

Johnsonboat · #3 02-16-2014, 06:50 PM

Smoke, the engine harness is rotten. all bare but np, my friend has one. My plan is to rewire, compression test, run it. then i will decide how much i will need to dump into it. I'm just getting price on kit. if its over $500 I will donate the motor and find a used yamaha. thank you

spareparts · #4 02-16-2014, 07:28 PM

while those were great motors in their day, they don't run well on the crappy gas we have now. Defiantly up the jets one size and run about two degrees less max timing. Its not a fix, but it will help a little

Destroyer · #5 02-16-2014, 11:23 PM

One other thing... Unless the transom on your boat has been reworked, I'm pretty sure it should be a 20" transom. Might just be my old mind having a brain fart, but I thought that they were 20" until the early 80's? Maybe someone else on here can shed some light on that?

As far as the engine itself goes, those old "tower of power" engines were awesome. Like Smoke, I also have an 1150. It's just sitting in my garage right now, waiting on a boat to put it on.

THEFERMANATOR · #6 02-17-2014, 09:13 AM

MOST transoms i nthe 70's were 20" in as 25" shafted engines didn't get popular until the late 70's. Up until then offshore boats had either an I/O or an inboard. It wasn't until the mid 70's that outboards came out with enough HP to push boats of the size that peopel would venture offshore in. For most lakes and such a 20" transom was plenty to keep the backwash out. I'm not saying they didn't have 25" shafts back then, there just wasn't that many.