1970 Johnson 40hp 40e 70a spark plug

[mrdog101]

1970 Johnson 40hp 40e 70a looking for what spark plug I need right now I have ngk b6s and What gap I need I seen 0.03 my old plugs ends are black​

What causes the spark plug end to be black is it bad gas or wrong mixture I used a mixture bottle or it could be the cheap oil the guy gave me might need some better oil to mix with the gas it smokes a lot to when at high revs in a bucket but wasn’t doing that last year on water

 

[jimmbo]

Welcome to iboats

That engine was originally speced for Champion J4J. Champion has changed their Numbering System, and I don't know what the latest Number is.
Is the Black Substance on the Plug, kind of Light and Fluffy, Oily, Dry?
It could be too much Oil, too much Fuel.
High Revs in a Bucket are not Synonymous with long engine life. That said running in a bucket is a lot different that running on the Lake. On the Lake, all the smoke is still there, only it doesn't come out of the Water near the boat.
A good TCW-3 Oil will often help reduce Smoke though, I kind of like lots of it, as it helps keep the Mosquitoes and Horseflies away. Ratio of Gas to Oil, is 50:1

 

[mrdog101]

 

[mrdog101]

And the water in the bucket looks like some type of substance on top like darkish color I can take a photo in the morning kind of looks like dark oil but I don’t know it’s my first boat just trying to get my idle running good so I can try to troll for walleye but it might be to fast to bottom bounce as when I go slower my engine cuts out I sometime raise the speed to keep it running would that be the low idle screw

 

[jimmbo]

I will assume your engine is a Mechanical Shift. The Idle Speed Stop and Adjustment is below the Lower Cowl on the Port side, just behind where the Throttle Cable connects.

From what I can see of the Spark Plug Electrode, it looks pretty clean. I would say the guck is Unburnt Oil, which is not uncommon.

Those 40s are actually not bad Idlers, but eventually will load up. Idle speed in gear is about 600-650 rpm. Speed of the boat at that rpm will vary depending on the Boat, its Weight, and also the prop pitch. However, choosing a prop is not done by what speed the boat goes at Idle. Picking a prop that puts the WOT rpm at 5000, is lowest Pitch you can run with out over revving. A properly adjusted Low Speed Mixture, will help the engine run better at Idle

 

[racerone]

A 1970 model 40 HP will troll all day long if in good condition.-----Does spark jump a gap of 5/16" on a test device ?----Post compression values here.----Is thermostat installed and working properly?----You did install a new water pump impeller when you bought this motor ?-----Installed new fuel pump diaphragm ?

 

[F_R]

The question bring back many old memories of 75 years ago when my dad would take us to Canada for walleye fishing. I remember we had to troll dead slow to get that orange and black flatfish plug down on the bottom. In my opinion, that 40 hp just isn't going to get it. They will idle slow, but the boat speed is too fast because of the large prop.

But back to the question, get that motor out of that bucket and on a boat on the lake where it was designed to be run. Very good chance it might be just fine. It isn't the plugs' fault.

 

[jimmbo]

The question bring back many old memories of 75 years ago when my dad would take us to Canada for walleye fishing.

Do you remember where in Canada you would go for the Walleye Fishing?

 

[racerone]

Well----I know a really good place in Ontario.----But I am not telling anybody.

 

[jimmbo]

A lot of the Sloughs, that are called Lakes in Alberta, have Walleye

 

[racerone]

Has cost me many beer tokens for fishing in ALBERTA.-----Have not caught anything I could eat.----A few pickerel to release.-----Good fishing , but lousy catching.

 

[F_R]

Do you remember where in Canada you would go for the Walleye Fishing?

That was Bob"s Lake, near Maberly Ontario. Back then it was pristine. I hunted it up again a few years ago. Frankly, it was disgusting.

 

[Ronniewhite]

That was Bob"s Lake, near Maberly Ontario. Back then it was pristine. I hunted it up again a few years ago. Frankly, it was disgusting.

That lake is about a half hour from me. Only fished it once about 20yrs ago. It a huge lake.

 

[racerone]

Development is allowed and has ruined many a pristine lake.------Development along rivers and lakes is BAD for wildlife.-------