1967 3HP Johnson Saprk Plugs and Tank Corrosion

[gitchi gummi]

First, thanks for all of the great info and opinions found here. I just received a '67 Johnson 3HP for FREE. A friend of the family dropped two 3HP off stating that they didn't run anymore. Thanks! Ignition is now rebuilt and we have spark and it fires. I am waiting for the carb kit to arrive. All lower end gears and seals inspected and lube changed.

So the plate on the front of the motor near the low speed idle knob states to use a Champion J4C, a forum search here and the repair reference book I have call for J6C, and the Champion book and web site call for J8C! I am not at all informed about the differences in these plugs. Why all of the inconsistency in recommendations? I ask for help mostly because I don't want to cause a problem with this great little motor.

Also, the inside of the gas tank is corroded. I poured powdery white junk out of it. I then attempted to rinse it out with some white gas and got lots of gunk out, but when I stick my finger in there it still feels real gritty on the inside. Does anyone have a proven way to clean this? Is there some magic petrochemical that I can use to restore the inside? I was thinking about trying to power wash it, but I think it will be really hard to get to all of the surfaces. Has anyone used an in-line fuel filter (other than the one that is supposedly in the tank)?

Thanks for any help with these two questions.

 

[freddyray21]

Re: 1967 3HP Johnson Saprk Plugs and Tank Corrosion

J4 was the standard plug and can be found. A J6 is just a hotter version of the same and a J8 still hotter. If you can't get a J4 then run a J6 not the J8. The take the fuel line off and just continue to rinse the tank as you are doing. A inline filter can be used. I recommend the small motor cycle filters.

 

[gitchi gummi]

Re: 1967 3HP Johnson Saprk Plugs and Tank Corrosion

Thanks for the info regarding the plugs. I got some additional advice on the tank corrosion from some motorcycle guys. They recommend using naval jelly (phosphoric acid) and putting steel shot (BB's or the like) in the tank and shaking it all around to clean out the corrosion. One must then rinse with- gulp- water to get the acid out and shake all of the shot out. Then thoroughly dry. I found a K&N 81-0222 right angle fuel filter that should work well as the gas line is very short.

 

[lindy46]

Re: 1967 3HP Johnson Saprk Plugs and Tank Corrosion

If you're doing a lot of trolling, a hotter plug will be less apt to foul out. I normally use J6C's. Also, you can gap them a little wider for trolling - .035-.040".

 

[tx1961whaler]

Re: 1967 3HP Johnson Saprk Plugs and Tank Corrosion

Thanks for the info regarding the plugs. I got some additional advice on the tank corrosion from some motorcycle guys. They recommend using naval jelly (phosphoric acid) and putting steel shot (BB's or the like) in the tank and shaking it all around to clean out the corrosion. One must then rinse with- gulp- water to get the acid out and shake all of the shot out. Then thoroughly dry. I found a K&N 81-0222 right angle fuel filter that should work well as the gas line is very short.

Does the 1967 have the in-tank fuel filter, made of sintered metal, on top of the shut-off valve.