'56 Johnson 7.5 fuel?

[ninhalo5]

Hi guys, I was wondering if anyone has suggestions on the best fuel to use for this engine. I just picked this engine up and ran it on a jon for the first time today.
The owners manual states to just use regular and not high octane because the higher lead may cause issues. It also says to use either outboard oil or automotive SAE 30 (not heavy duty) or cheaper oils. The instructions for mixing says put 1 gal of gas in a 4.5 gal tank, add 1 qt oil, mix then fill the rest of the way with gas.

Now I realize these directions were from 1956 and a lot has changed, like most gas you find is ethanol crap. Which I've heard not to run, but there's little choice anymore.

I ran 87 octane today in a 6 gal tank and added 3 bottles of (16oz?) outboard oil. Think that was a 16:1 ratio which I was told to run. It ran fairly well for the most part; a little jumpy WOT though. Not sure if that was the gas or if I need to make some adjustments here and there.

Thanks

 

[HighTrim]

Re: '56 Johnson 7.5 fuel?

Good for you for NOT listening to some "neighbour down the street" and trying to run her on 50:1!

16:1 is ideal for your 7.5hp. Keep it at that and it will run forever. Regular 87 octane is all you need.

The ethanol will only cause issues if your motor has not been tuned/updated. Clean the carb and install a new kit, change the fuel lines to newer ethanol proof ones, and you wont have any issues.

 

[ninhalo5]

Re: '56 Johnson 7.5 fuel?

Hi, HighTrim, The guy I bought the engine from is an older outboard restorer. His hobby is making these things like new especially the ones from the 20’s. He told me that the carb and everything has been redone, new hoses and o-rings. Under the cowl looks like it just came from the factory. About the only thing he didn't do was redo the paint, which is still original.
1 problem about his rebuilds are they are done at home and the water is in a drum, so running WOT is not a real option for fine tuning.

I might still go ahead and take off the carb, when I thought the engine was running pretty good I was gained on and passed almost like I was sitting still by a 8 h.p. now I wouldn't think that a half horse would make that much difference. That guy who passed me told me about a gas station about 20 min from my house which uses ethanol free gas. Do you think that would actually be better to run overall?

I think I'm gonna love this engine. I cruised around for a long time and the tank is still between full and 3/4... Sweet

 

[HighTrim]

Re: '56 Johnson 7.5 fuel?

If the carb is clean, recleaning it wont make it any faster.

That 8hp is more than just half a hp more. It would be rated at the prop, whereas your older 7.5hp is rated at the crank. So in reality it is alot more than half a hp more power. It also likely has a better prop. Alot of the 7.5s still have their original weedless prop, not great for top end speed.

If you want a little more top end, raise it up some. What pin are you running at? Shimming to sit higher on transom may help as well. Re propping as mentioned may be beneficial. What prop do you have on it currently?

They are great little motors. Your 7.5 will still be kicking when that newer 8hps plastic pieces are long broken

 

[ninhalo5]

Re: '56 Johnson 7.5 fuel?

Yeah his was a 8 hp Honda from the 80's I believe. Which if they are anything like their car engines... I see warpage in the future.

I'm not sure about the prop on my motor, Im guessing its a stock prop. It's small, white with a black bullet/cone thing covering the center.

I do believe I did have the engine sitting down too low. It was in the first notch by the transom, the front of the boat seemed somewhat high. Even my girlfriend mentioned that she felt like she was sitting much higher than me. Unfortunately I wasn't able to adjust the motor from the boat. When we where loading the boat, I moved the engine up to the next notch, we'll give that setting a try the next time out. Probably in 2 weeks. And it sounded a little boggy when taking off... Maybe boggy isn't the word, the exhaust/water was low and bassy( blurb blurb blurb ) well it kinda sounded like a car exhaust under the water.

Oh and recleaning the carb I would just hope to help get rid of he sputter or whatever it is, During WOT

 

[ninhalo5]

Re: '56 Johnson 7.5 fuel?

Was there any thought on using that SAE 30 oil instead of the 2-cycle as the owners manual mentioned? I always thought to never use automotive oils in anything other than automobiles due to it foaming, or being that its mixed in gas the foaming properties are reduced? Auto oil is a lot less expensive than 2 cycle.

 

[HighTrim]

Re: '56 Johnson 7.5 fuel?

Only use TCW3 rated outboard oil.

 

[ninhalo5]

Re: '56 Johnson 7.5 fuel?

Ok that's what I figured. Oh and I think I may have found part of the culprit making the engine jump during WOT. I took the cowl off today and found a good bit of gas here and there. It appears that the bottom carb adjuster was leaking. I tightened it down then out a little so I would be able to turn the knob when needed. Possibly one of the O-rings in there split or something. If it still leaks, I guess it'll be time to buy a rebuild kit.

 

[HighTrim]

Re: '56 Johnson 7.5 fuel?

There will be 2 packing washers behind that packing nut. They are replaced during a clean/rebuild. IF all else runs well, just add a washer and retighten. Get it set, then tighten down so it wont move.

 

[ninhalo5]

Re: '56 Johnson 7.5 fuel?

Update: I took the boat out yesterday and it ran worse than the week prior. I added 2 kids which brought the weight up by 85 lbs. I wouldn't think that would bog the engine down as much as it did.
When I got home I took a look and seen the carb was still leaking, I ordered a new rebuild kit for it that comes with updated needles and a float; should be here by thursday.

Today I decided to look over the engine. got equal compression in both cylinders YAY then checked the point and spark plug gap. There was one plug that was a little too closed and the other was just right, and the points were set to .023 not .020 as they should have been... well time to take the flywheel off. After taking the flywheel off the first thing that I noticed was the pretty new coils there, then I seen the green wire of the lower cylinder coil had a flat section and in that flat section was a small amount of wire showing. As smooth as it was I'm guessing the flywheel pinched it and has been rubbing against it. This maybe where my WOT kicking is coming from. Then on the black wire it was the same thing but worse; the black wire was cut almost all the way through and just hanging on by maybe 8 copper wire threads.

Well I guess it's time to replace that. I went ahead and ordered a complete tune up set. hopefully everything will be good as new once replaced

 

[Chinewalker]

Re: '56 Johnson 7.5 fuel?

Yep, that'll do it. Make sure those wires aren't pinched anywhere and are tucked down and away from the cam and flywheel.

 

[metriccrescentwrench]

Re: '56 Johnson 7.5 fuel?

Only use TCW3 rated outboard oil.

True, but that engine has been in use long before the TCW3 spec came out.

I need to see some photos of that engine. When I was a kid we had a 14 ft aluminum boat with a '56 Johnson 7.5, I pretty much lived in that boat during the summer.

 

[Crosbyman]

Re: '56 Johnson 7.5 fuel?

I fixed up a 1958 7.5 last winter and feed it AMSOIL synthetic at 24/1 .... on my annual trip for walleyes that little kicker ran so smooth and no smoke I could not beleive it. nice purring sound in the wilds

trolled it for about 20 hours without a hick-up pushing my 17..5 foot bass boat and two big guys & gear (75 ETEC)
that kicker is 47 years older than it's ETEC big bro. !!

and the little guy loves gas ...more than the big guy at trolling speeds... ho well....it runs great

next project ... a 50's JW I picked up for 20$ !! on KIJIJI.... BTW... looking for a prop

 

[ninhalo5]

Re: '56 Johnson 7.5 fuel?

I have a new question. As I'm putting in my points and stuff the bag of parts comes with 2 oil covered wicks and 2 little capsules of what I guess is black grease. What am I supposed to do with the grease? And I noticed I am missing one wick holder. Is that 2nd wick really imperative? The parts book don't even show the holder. I'm guessing the wick is just to keep that part of the crankshaft lubed and dirt free.

Thanks

 

[HighTrim]

Re: '56 Johnson 7.5 fuel?

You only need 1 wick, not 2. Just put the holder under 1 of the coils.

The grease is for the points pivot pin. Open the capsule, drop it over the pin, then back up and it will grease it. Not too much, just a bit. Then install the free part of the points. Keeps it running smooth.

 

[ninhalo5]

Re: '56 Johnson 7.5 fuel?

Great, thank you. Now I'll get that sucker put back together

 

[ninhalo5]

Re: '56 Johnson 7.5 fuel?

Well I got the engine all put back together. It still has this astigmatism thing going on, is this natural? Here is a vid of it running as it sits now. http://youtube.com/watch?v=HNtd6P50jmo

 

[nwcove]

Re: '56 Johnson 7.5 fuel?

a bit rough at idle, you possibly can smooth it out with the ls jet, or setting the timing to be perfect. and on a side note.....get that motor deeper in your barrel when testing.......i see it is pumping, but you should have the impeller housing submerged!!

 

[ninhalo5]

Re: '56 Johnson 7.5 fuel?

Hmm. I actually put in a new jet and this shaking was how it was prior, so there is really little difference with the new one.
I believe I got the timing right. What I did was turn the crank ( there was a spot labeled TOP) and lined the center of that up with the point arm resting on the crank shaft and set that to .020 then did the same on the other side. About the only thing I didn't change out was the needle valves and the spark plugs which all looked pretty good. I'm stumped. Well I'll take her out to the river tomorrow and try to make adjustments like the manual suggests is the best way to go.

 

[ninhalo5]

Re: '56 Johnson 7.5 fuel?

What a horrible day I had yesterday. Decided to go check out The Dam 4 area of the Potomac River, when we got there I was the only Jon boat there. Everyone else there had their nice $100k speedboats, I was thinking Ok this is a little embarrassing. Kind of felt like the Eddie Murphy Joke about the poor kid and ice cream lol. So I figured what the heck lets put her in the water, go exploring and get the engine tuned. I put the boat in the water and the lil' Johnson started on the 2nd pull ;yay. Well that's where the happiness ended.

Put her in full throttle and she went maybe like 3 knots/mph... Hmm this isn't right so I started tinkering with the carb and she started to sputter and I couldn't prevent her from shutting off. That was more or less the last time she really ran. I tried resetting the carb back to the basic 3/4 out and 1.5 out on the needles, no dice, I did actually manage to get her started 2 more times for a couple seconds each before my starter recoil spring snapped in 2 pieces and each time she ran really really rough like the timing was 180 out on a car engine. Hmm, lets take a look at these points again. Pulled out the feeler gauge with a tiny amount of drag at 0.020, felt like it could have been better so I reset both points. About that time DNR stopped by to play 50 questions with us. Now were getting a flock of people with more money than brains staring and laughing... They (DNR) leave and it's time to get back to work on the engine. Now this time at idle all I got was bang, clang, backfire shimmy then nothing. Tinkered for 2 more hours and she wouldn't start at all. And let me tell you it really sucked trying to wrap the pull cord around the flywheel to giver her a yank. I'm just glad I had emergency paddles and a friend with me.

So, now I have no idea what to do, I've followed everyone's advice I've found here and in the owners and shop manuals.
Back to square one.