1957 7.5 johnson-calibrating

[rookie85]

Ok so i'm pretty fresh at this whole outboard engine thing. I rebuilt the carburetor on my 1957 7.5 johnson and slapped it back on the engine. It took me about 30 pulls to get it started and finally it started, but I have no idea how to calibrate it and keep it running when I shift to drive. I got a book from the library and it said to start the low-speed needle 1-1/2 out and the high 1 turn out. Is this right cause it doesnt run well when I do that.

 

[jbjennings]

Re: 1957 7.5 johnson-calibrating

Rookie,
I can tell you with confidence that if you haven't looked at your ignition yet, you're spinning your wheels. You should purchase a $6 spark tester at autozone and see if both wires will make a spark that will jump a 1/4 air gap on the tester. If not, you need to fix your ignition.
You are herey granted a special dispensation to peek into the "top secret files" at the top of the johnson forum which you're in right now, and look at the carb setting thread, and the coils/points thread. ---anybody can look and no password needed....... Those 2 should get you going. That is a really nice motor, btw! I know you're going to like it. Welcome to iboats, BTW!

JBJ

 

[wbeaton]

Re: 1957 7.5 johnson-calibrating

How about a little back ground on the motor. How long have you had it? Why did you rebuild the carb? Did it ever run right on a boat?

The coils on those machines are always bad unless they've been replaced. If they are cracked, sweaty or discoloured they are bad.

When did you replace the water pump impeller last?

 

[rookie85]

Re: 1957 7.5 johnson-calibrating

Well i've only had it for a couple of weeks. I recieved it as a gift from an uncle who has past. As far as I know it was only used a handful of times. Another uncle of mine used it last summer and said it ran, but had an idle problem and that the carb should be rebuilt. which I did. I can get it to run its just that I cant keep it running when I go to shift into "Forward". Plus in my opinion I don't think it does idle very well at all. Really smokey as well.

 

[lindy46]

Re: 1957 7.5 johnson-calibrating

Yup, check spark and look at those coils.

 

[wbeaton]

Re: 1957 7.5 johnson-calibrating

Probably bad coils. They spark enough to idle, but not enough to run. Take off the rewind starter. Under it is the flywheel. There is an inspection plate on top of the flywheel. Remove it and take a look at the coils. If they are bad they will likely look like the ones in the attached photo. You should have also cleaned and set the points as part of your initial tune-up. Dirty points = poor/no spark.

You need to replace your impeller, too. That means removing the powerhead. Since you will have the powerhead off you should also replace the cork gasket and o-ring that sits on top of the driveshaft and makes up the lower crankcase seal.

Overwhelmed yet? If I haven't already sent you the parts manual for your motor then send me a PM with your email address. You will find it very helpful.