Can you visually ID a 20 pole tach?

[huskerdaninva]

Hey all, I've got a question...can one visually tell if a tach has a setting for 20 pole use? I have a 1969 Chrysler 70 hp model #7071 and was looking for a replacement tach & speedo set and stumbled on to a set from an old Force set up for cheap. (I think the guy said they came from an 80's Force 85 motor and should work with just about any outboard motor. Boy am I naive sometimes!) At the time of purchase I didn't realize/know that I needed a 20 pole tach for my old motor. So the tach I have now has a setting on the back for 1-2-3-4 and currently is set to "two". Is there any way I can visually determine what style or how many poles? Thanks in advance for any help in answering my question. :redface:

 

[pnwboat]

Re: Can you visually ID a 20 pole tach?

I don't know of any way to visually determine if a tach is compatible. You can do trial and error to see if you get a reasonable reading, say at idle. If tach reads 3000 RPM at idle, then it's probably not the correct setting. Not the most scientific way to check, but it's worth a try.

 

[NYBo]

Re: Can you visually ID a 20 pole tach?

A mid-80s 85 HP Force would have a 20-pole alternator, so if the tach worked properly with that engine, there should be a setting that works with your motor.

 

[gunterm]

Re: Can you visually ID a 20 pole tach?

I've got a 55hp same year and never got even the 20 pole special I bought to work at all. Tiny tach seemed like a solution but I haven't tried that yet.