questions regarding 1960 merc300 rebranded as merc350

[Lectrick]

Ok, the alternator worked out of the gate, but the starter motor did not. Starter motor was functional, but one ear on the starter housing was broken off.

I found that out after trying 2 starter motors with it. Long story short, I couldn't get the bendix to kick out the gear. I solved that. I went through a number of them and used heavy gauge jumper cables from a car battery to check them, they didn't work.

Now I have a 1960 merc300 re-branded as a Merc350 (learned this from the serial number and the Oldmercs site) and it starts fine, but no longer charges the battery. I had to tag in a great deal of heavy gauge wire to make the new starter work.

I have a diagram of the wiring, but what I need to know is where to start - stator? I have no clue. I'm used to working on old cars/trucks, but I don't know where to start to figure this out. The junction of the wires at the engine is old and corroded, but what I want to know is where I check voltage with the cover off when I'm running the outboard in a garbage can - it won't take muffs. What should I see at idle, and will it even charge at idle? I'm clueless.

I got this thing a while ago, and I was so busy making the electric start work that I might have burned out something... i.e. I checked the main power connector for the harness and it was loose. I don't even know what can burn out in something like this. Any help is appreciated.

Also, it doesn't run like it used to... I decarbed it (ran it on .75 gallon of gas, can of sea foam, and mixed in the 2 cycle gas) and it was smoking like hell. I would run it for 15 minutes, stop it for 15 minutes, then repeat over and over until the gallon was gone.

It runs much better now, it smoked the whole time, and I'm lost as to where to start next. I'm pretty good with engines, but new to 2-strokes. Mostly what I need to know is how to make it charge again, and I'm good at rebuilding carbs, I think it has Tillotsons in it. Charging is my primary concern, and any other recommendations are great to hear.

14" Lone Star runabout, 1960 Merc300, any tips are appreciated. I've done a search on the alternator, on the engine, and this is an old beast which runs OK at full throttle (22 mph on gps) but it could be a lot better, and it's not charging the battery since I solved the electric start.

Anything you can give me will help.

Lectrick
Mike Gilbertson, lmike@tek2go.com, 612-308-6136

 

[1960 Starflite]

Re: questions regarding 1960 merc300 rebranded as merc350

Take the two wires coming from the stator (under flywheel) off of the rectifier. Using a volt meter set on AC voltage conect the red lead to one of the stator wires and the black lead to ground. There should be some AC voltage at both wires from the stator. You might have to move the engine to fast idle to see it. If you have AC voltage there, hook them back up to the rectifier. Set the volt meter to DC, red lead to the third post on the rectifier and the black lead to ground. Run the engine, you should see DC voltage, around 14.5 volts at speed. If there is no DC voltage, you'll have to pull the rectifier and check it out. It has diodes inside and there is a process to check in most outboard manuals.

On another note, here is a list of parts I replaced on my 1960 300, s/n 1355xxx it may help you and others later.
FUEL PUMP VALVE KIT W/GASKETS 21-30430A
CARBURETOR GASKET KIT SIERRA 18-7006-1
NEEDLE & SEAT SIERRA 18-7057
WATER PUMP IMELLER 47-89983T

Bought from Oldmercs.com

Smoking ? Fuel mixture is 50:1

 

[Lectrick]

Re: questions regarding 1960 merc300 rebranded as merc350

Thank you very much for your response, you've given me somewhere to start As far as the smoking goes, I was making it smoke on purpose as I was decarbonizing the engine. I have more of that to do

Thanks for the tips on the part numbers too. Bob Grubb mentioned that I should change the upper and lower crankshaft seals as well...

 

[merc850]

Re: questions regarding 1960 merc300 rebranded as merc350

Here's the rectifier check

 

[Lectrick]

Re: questions regarding 1960 merc300 rebranded as merc350

thank you very much I'll report back when I get a chance to check it. Just did some work on another boat that made me think I need to replace the fuel line from the tank to the engine. I guess I should be sure it runs well first and check the compression on it before I start worrying about the alternator.

 

[Lectrick]

Re: questions regarding 1960 merc300 rebranded as merc350

Thank you very much for the diagram !!!

 

[Lectrick]

Re: questions regarding 1960 merc300 rebranded as merc350

Ok, new problem. I decided to check the compression (90 psi at all 4 cylinders) before I went further with this outboard. I was happy enough with the compression (may be a bit low, but it's even across the board). However, when I pulled the plugs to do it, I noticed that my #4 plug was shiny and new as the day I put it in - I replaced all 4 plugs about 2 months ago.

So I checked, and sure enough, no spark on #4. I then took that plug and put it on another plug wire, and it sparked just fine.

I can't afford a service manual just yet - but it looks like all I need to do is replace my plug wires. Done it a million times on other engines (mostly automotive), but I can't figure out how to get the plug wire out of the top of the distributor? Do I need to remove the distributor to do this? 1960 merc 300 "updated" to merc 350 (s/n 1327645).

 

[Lectrick]

Re: questions regarding 1960 merc300 rebranded as merc350

Turns out the #4 spark plug wire was damaged, it was stuck between the bottom housing and the accelerator lever that swivels the distributor (I don't know proper terminology here). Insulation was worn through to the wire and #4 was grounding out there between the dizzy and the spark plug.

I *still* need to know how to change that wire, but for the time being I wrapped the heck out of it with electrical tape, moved it out of the way so it wouldn't encounter the same problem, and voila - went from 21-22 mpg top speed to around 28.

Obviously, I'm using all 4 cylinders now. Next is for me to check the charging circuit per Starflite and Merc850's posts. I obviously need to get a service manual, but it will be a couple weeks before I can afford one.

I will (DO) have any number of other issues to chase down - while playing with the trim and my newfound horsepower, I discovered that I needed to bring the trim down 1 hole (it's manual with a pin) and replace the ballast in the bow which I had previously removed. The next higher trim setting got me more top speed but made it porpoise like crazy. I want to say I can get 31 MPH or slightly more out of it with the proper trim, height, and prop. I've been doing a lot of research there.

All that being said, with my temporary electrical tape dizzy wire fix, I got another 6 or 7 MPH out of the top end.

At WOT for an extended time, primer bulb goes flat and motor bogs down. It takes some time. From what I've researched - fuel line, fuel sender in tank (or get a tank), and fuel pump kit should help that.

Also, when warm, after I let it sit for a bit, it *will* start up, but not without being hormonal. Also, at that time, it will still bog down or outright kill when I put it into gear and give it what for.

I realize I'm likely looking at a carb kit too. I'm just trying to start with the cheapest/easiest stuff.

My basic goal is: Get it to run nice. Fuel delivery is an issue. Fuel pump rebuild kit is cheap and that's easy to get at. I can get another fuel line with bulb for around $25 on Ebay. I can find the connectors I need. After that, I see the carb kit on Oldmercs.com for around $20. I have to ask them if that's for both carbs or do I need to buy 2. Then comes the fuel tank, depending which is cheaper.

Then I get to check the points. I'm not sure how difficult that is on this engine. I'm still not clear that the points are in the dizzy (although that's what I suspect from working on old cars/trucks).

Lastly, although my compression is very even (pretty much dead on 90 psi) on all cylinders, I've never done much work on a 2-stroke. Is that a fair compression? What comes into play? Do the reed valves affect that much? Might I be looking piston rings at that point?

Thank you all VERY MUCH for your time and patience. You have motivated me to tinker with this engine and I have already seen great results with minimal effort.

 

[1960 Starflite]

Re: questions regarding 1960 merc300 rebranded as merc350

You have to pull the magnito to work on the ignition system on that engine. No big deal, there are 3 or 4 small bolts holding it to the adaptor and it will drop down and out. You don't have to pull the belt and you can't get it out of time. There is a missing spline on the input shaft and will only go back one way.

Once you have the mag in hand, remove the bolts holding the cap to the mag, be very careful with it, NLA and $$$$ if you find one in good shape. There is a small brass set screw holding each wire in place and there are o-rings around each wire. Go to your local NAPA store and purchase a length of solid plug wire, boots and ends and replace all as this is the time to do it. Don't even try to find new points at a fair price. My local marina had 5 sets on the shelf at $50 each. That was ten years ago. Part # is 393-1504A 11. Oh, and be very careful with the rotor also, some on Ebay now at $200 each.

The price for the carb kits is EACH. If you want to see if the mag is working after you adjust the points, just hold it in one hand and spin the input shaft. It will sent a jolt up your arm, so don't drop it. Don't ask how I know that. I think the point gap is .008-.010, it should be stamped inside the mag. Make sure the felt lube is against the cam.

Compression isn't too bad for an engine that old. Reeds are on the crankshaft, so they would be part of a rebuild.

Tom on Buckeye Lake

 

[Lectrick]

Re: questions regarding 1960 merc300 rebranded as merc350

Thank you very much for your input, Tom. I haven't had time to work on it lately but your tips are greatly appreciated