Setting air gap on my 30hp johnson

[Smokercrafty]

Hey guys, I have a '90 Johnson 30 hp that I'm installing a new trigger on. Problem is, the sensor has elongated holes, and I've read it needs to be spaced properly (0.010" - 0.020") away from the flywheel.

Point being, from factory, they use what is called a "locator ring" to simulate the flywheel while it's off, so this air gap can be properly set. A long shot here, but would anyone here possibly have this tool to loan out?? Part number is 553-4994 fingers crossed......

If not, has anyone done this job without using it???

[DanD]

If you can make out the screw head marks on the old trigger and the new trigger is identical; you should be able to match mark the screw positions on the new trigger.

They're giving you .010" variance so it should fall into the spec.

Another way would be to find a .015" piece of paper (cardboard from a cigarette pack) and glue it to the sensor tip of the trigger. Now with some trial and error set the trigger so that it touches one of the vain of the flywheel. Just enough that when turning the flywheel by hand back and forth past the sensor you can feel the vain slightly touching the sensor.

Voltage will still be induced into the trigger through the paper and after the first start the paper will be worn off; giving you your proper air gap.

 

Dan.

Edited August 2, 2016 by DanD

[Smokercrafty]

Thanks for the tip Dan. I'll have a look at that tonight. What I never checked was if if I could set the trigger, and see if the flywheel would sit low enough by hand to check the gap. I doubt it, but your idea sounds plausible and the route I'll most likely take.

After a little research, another method was wrapping a flexible piece of strapping around the stator and charge coil possibly simulating the locator ring. Other than that, I've also heard of wiping the trigger face with tire crayon and go from there.

Your thoughts?

[Tybo]

I use a feeler gauge,

[Big Cliff]

I use a feeler gauge,

I don't do a lot of work on outboards but when working on lawn tractors (and any other small engines) I use a feeler gauge. Loosen the screws on the coil/trigger, place a 12 thou feeler gauge between the coil and the flywheel, rotate the flywheel until the magnets line up with the arms on the coil at which time the coil will snap tight against the feeler gauge, tighten the screws, remove the feeler gauge/flywheel and you should have your 12 thou gap.

Edited August 2, 2016 by Big Cliff

[DanD]

That's the point, when the flywheel is in position; you cannot get to the trigger.

That's why this tool is needed.

Dan.

[Big Cliff]

That's the point, when the flywheel is in position; you cannot get to the trigger.

That's why this tool is needed.

Dan.

And that is why I don't do much work on outboards, special tools are needed to do a lot of it!

Edited August 2, 2016 by Big Cliff

[Smokercrafty]

That's the point, when the flywheel is in position; you cannot get to the trigger.

That's why this tool is needed.

Dan.

Thanks for showing them Dan. But yeah Cliff, I'm a tradesman myself and have no issues if it was straightforward, but as Dan said, you aren't able to use any devices while the flywheels on. I appreciate your input nonetheless my friend.

So Dan, with my 2 other suggestions, and yours, which route would you go? I was gonna bring a "Slim Jim" home tonight, and see if I could wrap it around all 3 parts. Being thin and flexible, I'm hoping it may do the job.

Edited August 2, 2016 by Smokercrafty

[DanD]

Anyone of these ideas will likely work; just make sure that there's enough clearance not to smak your new trigger.

 

Keep it fun and you'll figure it out.

 

Dan.

[ecmilley]

yup ciggy pack paper is pretty much 10 12 thou. used it for years setting coils, feeler gauges are misleading anyway unless your using non-magnetic brass ones.

pull wheel tape paper in set and tighten pickup lift flywheel remove paper reinstall and make sure no contact go fishing

[Smokercrafty]

Thanks for showing them Dan. But yeah Cliff, I'm a tradesman myself and have no issues if it was straightforward, but as Dan said, you aren't able to use any devices while the flywheels on. I appreciate your input nonetheless my friend.

So Dan, with my 2 other suggestions, and yours, which route would you go? I was gonna bring a "Slim Jim" home tonight, and see if I could wrap it around all 3 parts. Being thin and flexible, I'm hoping it may do the job.

 

Well thanks boys.... Sure puts my mind at ease hearing from other sources. Thankfully EC, this is my spare motor, so the fishins being done, while this one is gettin fixed. Just a note to any who may be reading this thread, this motor will probably be up for sale once I get it running. The lower unit has been rebuilt, and just waiting to go on, once this is done. I will confirm cylinder pressures, but before going out of service, I checked and they were 145psi a piece. Just a little tidbit of its history. Also, it's a 1990, remote start, long shaft.

[DanD]

yup ciggy pack paper is pretty much 10 12 thou. used it for years setting coils, feeler gauges are misleading anyway unless your using non-magnetic brass ones.

pull wheel tape paper in set and tighten pickup lift flywheel remove paper reinstall and make sure no contact go fishing

 

I usually don't worry about the paper and just leave it there to be chewed up and spit out after running a few minutes.

Just like the 3.5Lt Chrysler's camshaft position sensor; they're induction coils/triggers/sensors, as long as the magnetic feild can penitrate, it will form an induced voltage.

 

Dan.