Which tach for my old Johnson 60 hp?

[Larson67]

Hi - I've got a '67 Johnson 60 hp (model VXL-13A) with the alternator under the flywheel. I'm looking for a tach but not sure which would work. Some have a selector on back to choose a 2, 4, 6 or 8 cylinder motor, and some have selectors for the number of pulses, like 1, 2, 3, 4, 5, 6, etc.. Others say they are for 12-cycle setups. I'm hoping to find an older gauge that will fit the old Larson boat I have, or if I have a newer one, but am thoroughly confused by all these types and what will fit what. Can someone please fill me in on this or point me in the right direction to read up on it? Thanks!

 

[alldodge]

Hi - I've got a '67 Johnson 60 hp (model VXL-13A) with the alternator under the flywheel. I'm looking for a tach but not sure which would work. Some have a selector on back to choose a 2, 4, 6 or 8 cylinder motor, and some have selectors for the number of pulses, like 1, 2, 3, 4, 5, 6, etc.. Others say they are for 12-cycle setups. I'm hoping to find an older gauge that will fit the old Larson boat I have, or if I have a newer one, but am thoroughly confused by all these types and what will fit what. Can someone please fill me in on this or point me in the right direction to read up on it? Thanks!

You need to figure out how many poles is on your alternator, From what I'm finding as a non-expert it appears to be 10 or 12 poles. You use this to set the switch on the back of the tach. Also look to see if it is for a Johnson outboard such as this one

 

[Silvertip]

Doesn't need to be for a Johnson. Tachs are very generic. Do not buy a tachometer for a car.

 

[Larson67]

Okay thanks guys. How do I find out how many poles my alternator has? The manual's got nothing.

 

[Silvertip]

Not sure but it will be either 5 or 6. The dial on the back of the tach allows you select the number of poles so that's not a consideration on a generic outboard tach.The instructions that come with the tach (Faria for example) has a chart that tells you what those numbers are.

 

[Larson67]

Okay, got it. Thanks, guys. Off to that electronic bay...

 

[Silvertip]

Actually, the numbers are not the number of poles but rather the number of pulses per engine revolution. 5 or 6 "pulses" equates to a 10 or 12 "pole" alternator.

 

[Larson67]

Okay, Thanks Silvertip. Found a generic one that will work- has original installation instructions, too. Love it when I learn something. Larson67