Blackmax 200 - Prop issues or something else?

[dsiekman]

Okay...so the gauge is an older Faria 7000rpm. Back dial has settings from 1-6p. Currently set on 6p. Motor should be 12p from what I've found. Wrong gauge, wrong setting, or wrong prop? I understand redline is +/- 5500, so it shouldn't spin up to 7000 with a 23 pitch prop.

 

[Maclin]

If the gauge is set for 6 poles and the motor stator thingy actually has 12 poles then the tach will be reading exactly half by my calcs. Are there any other switches on the back of the tach? like x2 or something. Just guessing.

 

[dsiekman]

No Title

If the gauge is set for 6 poles and the motor stator thingy actually has 12 poles then the tach will be reading exactly half by my calcs. Are there any other switches on the back of the tach? like x2 or something. Just guessing.

I'll have to poke my head back under and take a look. I would have sworn the gauges were Faria, but they may be Teleflex. That said, I found some pics on line that show the back of a teleflex gauge with the same 1-6P settings. What I had not been able to see on mine is that there is also a "6C" setting next to 3P which, per the note on the back of the tach means six cylinder. What I need to verify is that the indicator needle is in fact pointing at 6P as 6P sits opposite 6C. Very confusing, I know.

I borrowed the pic below from the interwebs, but you will see what I mean. Hopefully will get back down today to verify.

 

[Maclin]

Yeah, that is a fairly common double duty tach for inboard 4cycle engines with coil triggering, and Outboards with alternator triggering. The "C" settings are for the coil triggered 4cyl automotive style inboard engines. Being an Outboard, yours triggers the tach with pulses from each pole of the alternator. I would have to do more research on the 12 pole outboard alternator thing. Maybe the boat tach is just a little older than what it can handle from newer motor alternators.

 

[dsiekman]

Looking at the specs for that tach it sounds like it will not operate with most large 2 strokes. Is there a direct correlation where I can just do the math until I replace it? Like 6p is double the reading of 12p or something like that?

 

[Maclin]

I think so, that is what you are seeing now, probably. At the 6p setting it will be double. Problem is that tach face won't go high enough to be useful. Look up Tiny Tach, those are pretty easy to hookup for temporary use as you dial in a prop.

 

[dsiekman]

I think so, that is what you are seeing now, probably. At the 6p setting it will be double. Problem is that tach face won't go high enough to be useful. Look up Tiny Tach, those are pretty easy to hookup for temporary use as you dial in a prop.

I checked out the website but I'm not sure the Tiny Tach is capable of running a 12 pole, either. I have also heard it referred to as 12 pulse (assuming that is 12 pulses per rev), and the Tiny Tach only does 8. Might just have to search Great Lakes Skipper or Ebay until I find the right tach.

 

[Maclin]

Tiny Tach should have an install that uses just one spark plug wire, that is the one I was going to get then sold the boat.


"Attach the Tiny Tach to your motor with the supplied rivets and attach the ground clamp (white wire) to a suitable ground. 2. Wrap the red wire around a spark plug wire with only two wraps. Make one wrap around the red wire to hold it in place and cut off the excess red wire."

 

[Sea Rider]

Hardline Hour/Tachs HR-8062-2 model can work up to 8 cylinders OB's, includes many sparks per revolution settings. Just set N? of cylinders, set spark firing per revolution to desire setting with OB-Off and voil?. Much faster to install as only need to wrap 4 turns on any spark plug cable and trim wire excess if liking.

Happy Boating

 

[dsiekman]

Thanks!

 

[dsiekman]

Solved. Tach was bad.

 

[Chris1956]

I would expect that 23" pitch prop is too much pitch for your boat/motor combo. Does she turn 5200+ with a normal load at full throttle?

 

[dsiekman]

I would expect that 23" pitch prop is too much pitch for your boat/motor combo. Does she turn 5200+ with a normal load at full throttle?

You would be correct. I was getting about 4700 with myself and my son (4 years old) and about a half tank of fuel. I was getting about 35-37 mph on gps depending on running with or against the tide. Idle was about 3.5 mph which is too fast to troll for stripers. Smaller prop should solve both issues