Sorry Mike, Dan is going to use it.

MercuryMarc wrote:

Dan,
This probably doesn't apply to your motor. But for my Mercs I had to add more wraps to get a clean reading. But then testing three different RPM gages. a tach, dwell meter,and a Tiny Tach all at the same time I found the extra wraps were giving a false reading, " higher RPM than what was being produced.

I have a Tiny Tach that probably has about two years left on it. If you want it PM me your address and I will give it to you.

Marc,
If Dan does not take you up on your offer I would like to try a Tiny Tach
 

I have (or had) a visual tachometer - the type used for industrial maintenance on electrical motors.  You put a white dot on the motor shaft (or whatever is spun by the motor) and the handheld instrument watches for the dot to go by.

I guess you could put a dot on an outboard flywheel and point the meter at the flywheel to get the RPM of the flywheel.  My father in law gave me one of these instruments a couple years ago.  I can’t remember if he wanted it back or not, ie I don’t remember if I still have it.  I will check in a couple days.

Locomotion wrote:

Marc,
How did you determine which instrument was right?

Well it started with my brand new dash mouted tach on my Hawk, dock buster. I was pushing a good amount of water, " almost ready to pop up on plane. And my tach was reading about 1,500 RPMs. That was my first sign of a false reading.

Then back in the driveway I had about nine wraps on my Tiny Tach, way to many. and my dwell meter. " Take the plug wire off And put this loop around the wire". 
My TT was reading way to high, just by tribal knowledge.

And my dwell meter reading was in the middle of the two and seamed and sounded about right.

I trust the old Merc-O- Tronic dwell,and RPM machine. I used this on the monster a few weeks ago. And will test it to my new dash mounted gauge I have to install too.

 

Marc,
How did you determine which instrument was right?

Dan,
This probably doesn't apply to your motor. But for my Mercs I had to add more wraps to get a clean reading. But then testing three different RPM gages. a tach, dwell meter,and a Tiny Tach all at the same time I found the extra wraps were giving a false reading, " higher RPM than what was being produced.

I have a Tiny Tach that probably has about two years left on it. If you want it PM me your address and I will give it to you.

MercuryMarc wrote:

Great photos Dan. 

Did Joe give you any tips on a different prop?

That little boat is sweet!

Thanks Marc.

I used a knock off tiny tach 2 years ago and was getting about 5,600 rpm. Joe mentioned that the knock offs have been found to be inaccurate and suggested that I use a real Tiny Tach as they have been found to be more accurate. I though I may have been running a bit rich at 3/4 throttle but I believe both Joe and Ray agree that the motor sounds fine at 3/4 throttle. I have been steadily adjusting trim out by 1/12 inch increments to get the bow up on the Fire Fly and as you can see in the photo that Joe took that my bow is just up a little bit, but it could be up just a bit more but may not be doable. 

 

Great photos Dan. 

Did Joe give you any tips on a different prop?

That little boat is sweet!

Joe McCauley., Ray and I went to White's Creek to do some speed runs past Joe, in the name of research. 

Photos by Joe.