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Dwell/Tach Meter Wire Hookup?

Retiredat49

New member
I have a '89 Johnson 50hp, 2 cyl, I cannot find in my manual or on the internet instructions regarding the correct hook up for the two wires from a "testing" tach to this engine in order to get the rpm for tuning low and high end.

I have found different opinions (i.e. red to starter or hot, blk to grnd, and so forth), but as on older cars the distributor-to-coil offered the intermintant spark. This engine does not have points or dist.

I am also wondering how a marine handheld "tach" is designed differently. I dont want to formulize an auto tach base on 8, 6, 4, etc. The manual shows a pic of one, 2 wires.... but that is it

Who knows ?
 
Look up Tinytach.Your auto dwell/RPM meter wont work on outboards or any 2 stroke.There is a way to drill a hole in the plate and hook up a OHM meter to set the points.I just set reinstall the flywheel and then use the timing light,if they are off I will redo them removing the flywheel.RPMs the tinytach works great! It reads sparks traveling through the plug wires,Each spark is one revolution.
outboard tach measures??? I always forget either stator pulses OR ?????? someone will reply
 
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This engine does not have any points.
There are however some ways.
Normally the outboard tach reads the charge frequency from the alternator system (6 pulses/rev)
If you do not have an alternator type tach, you may use a multimeter set on HZ (frequency)
Divide by 6, multiply by 60 (use the yellow/gray signal wire from stator. If your multimeter has an induction wire, coil it around one of the primary leads (still in HZ) and multiply by 60.
If you have a timing light with built in rev counter, set it on 2-stroke or use 4-stroke and divide by 2 and you get the reading.
 
I saw the Tiny Tach, cool idea, but a guy on Utube showed one then started having trouble reading the correct rpm,,,,,
However, I cannot believe in my manuals it shows the Tachometer/Dwell as a common tool, but in neither the Clymer or Outboard Marine Corporation Service Manual does it explain how to hook up a Dwell/Tach. The J 50 doesn't have pts, but to tweak the timing an accurate rpm is needed, especial for high rpm. I have not found any answers to what a marine tach is vs the auto,, (and there is a difference), I would rather not go thru a rigged calculation -how about using the correct tool for the job, no offense- I just want to try the designed method first, ....I did find however, a description of using the gray wire from the T. Strip, for a tach and will try hooking up a test tach to it, but all this 4 cyl 6 8 auto is not my way of dependability.......anyone using a Tach/dwell meter to test rpm for timing and tune up?
 
Well, so far I did find an instruction to hook up the lead to the coil "high tension" wire. I am not sure what "high tension" means,....wire to plug or pre side?

As the Clymer electrical schematic shows a gray wire running in this model for a tach, I do not have a gray wire on the T-bar. But I do have a gray wire running to the alarm via the thermostat -just a note for using manuals there are variations !!!

But in addition, I also found out that a tach will run from the Number 2 terminal on the T-bar. So I am going to go with that.

FYI: the Clymner has wiring schematics, the Outboard Association Servie Manual does not, however, it is far better for everything else mechanically and more....... I will post again after testing and tuning,,,I also need a test prop if anyone has one to sell.....1989 50 hp, Johnson.......thanks
 
Yeah, I see what you mean, I replied abaout the # 2 screw on the T-bar, which is a yellow striped wire, I will double check,,,I dont have a multimeter with HZ reader, thats what I should have,...the calculations woould be the smae to just multiply by 10. But I think I see what you're getting at: divide 6 becasue there are 6 arms on the stator, multiply by 60 b/c 60 Hz???
 
Well I clamped onto the #2 T-post, (yellow stripe, Manual says gray ?) and no signal in the tachometer on on the multimeter while idling.

However, as i try to idle by hear, the advance lever does not reset as far back as I can push it. This is while the idle and idle throttle lever is at a minimum. So I have this sruff at free fall right now, is there a visual trick in knowing where to have the advance lever linkage point while idling? Is this question confusing? I tired to post a picture, but didnt go though.

As I move the advance leverage manually, the motor sputters and misfires, I know there should be a predetermined spot.
 
Is there a idle stop screw on the throttle side of that motor? it may need backing off.That advance lever is to be set with the link and sync
 
well this is my 4th attempt to get a photo, the forum keeps logging me off and says login.......I cant seem to figure out how to get a photofrom pbkt into the forum, The forum says to load jpeg, gif and etc, but Im not successful yet. Yes there is the idle screw, i have it recessed for the time being, as the manual says to, ( it is one of the last things to set).
In a pic I want to show the space that the spark advance lever can move while linkage is set to idle, cam rod back and carbs in closed position. I think that the spark advance lever(rod) does not retreive all the way back in idle position-but Im not sure. I can set the engine to idle by hear, but its in the throttle up, i start to get cough and sputtering. My clest boat repair shop is 100 miles, they told me they do use a Tach, but adjust by hear......mm i can do that for idle but not wot. I hate to run it over there for them to try and set it by sound.........mmmmm not sure where Im going with this thread now......lol
 
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