What Pole setting?

[puddlesplasher]

Hi all,

Johnson 30HP O/B, 2 spark plugs, new tacho to be fitted to existing wiring. Max revs on Tacho is 7000.

What pole setting do I use. I found an old post on another forum that suggests 7000 revs is 5 Pole, 6 is 4, 5 is 3 and so on.

Please confirm the correctness of this.

Currently my tacho at WOT only shows 3300 revs and has always done this. However I can only obtain approx 10 knots max at WOT on a 16.5ft Microplus weighing approx 900kg with 2 adults and all the fishing gear aboard.

It has been suggested that I should have more speed than this as my 3hp gets me moving at 4 knots.

THis post is on the assumption that the tacho is defective.

 

[boobie]

Re: What Pole setting?

On your mtr the tach should be set to position 5. Also check to see if it's running on both cylinders.

 

[puddlesplasher]

Re: What Pole setting?

TY Boobie.

Is there anyway to have the needle sitting bang on zero? Currently it is at 2000 revs in the box.

I believe it drops to the idle speed upon starting the O/B.

 

[puddlesplasher]

Re: What Pole setting?

Also check to see if it's running on both cylinders.

How do I do that? Please keep it really simple. :facepalm:

 

[jgriner]

Re: What Pole setting?

TY Boobie.

Is there anyway to have the needle sitting bang on zero? Currently it is at 2000 revs in the box.

I believe it drops to the idle speed upon starting the O/B.

my tach shows like 200 rpm with the key off, then as soon as i turn the key it goes straight to 0, untill i start the motor.

 

[boobie]

Re: What Pole setting?

When it's running pull one plug wire off at a time and see if you get equal drop between the cyls. Use a good insulated pliers. When you get the tach installed properly it should go back to zero when you turn the key on.

 

[puddlesplasher]

Re: What Pole setting?

When it's running pull one plug wire off at a time and see if you get equal drop between the cyls.

What do you mean an equal drop? Do I listen for it or use the tacho and see what revs at a specific point?

 

[boobie]

Re: What Pole setting?

You can hear it when the cyl drops. Your tach may not be accurate enough to pick it up especially at slower speeds.

 

[Barnacle_Bill]

Re: What Pole setting?

The number of revs has nothing to do with the tach setting although outboard tachs usually have 7000 RPM max. The tach runs off pulses from the stator. You have a 10 pole stator so the tach should be set for 5 pulses.

 

[boobie]

Re: What Pole setting?

Read my # 2 post.