Tach Hook-up

[Jim Shepard]

Found this "vintage" tach in an antique store. Supposedly, it works. Never heard of the brand (Blue Chip) and can't find any info on the internet. Don't even know if it's automotive. Looks like it might be from a boat. It does look old school and at least it doesn't rev to 8-9,000. It's got three wires (white, green, black). Anyone know how I'd hook it up to test?

 

[greg g]

Blk ground

Grn to coil. Might be ground sensitive and not work on pos grand

White to ign on hot for power and light.

 

I think blue chip was made by sun for places like western auto sears etc.  Colors are almost spot on with an old sun dash mount I have.

Edited June 22, 2017 by greg g

[Frank's 49]

My guess is, it will work with + or - ground.  The question is, what number of cylinders was it set up for?  The number of spark impulses per minute will translated to different rpms. Does it have any sort of selector switch on the back (or a model number you can research? 

[Don Coatney]

This might or might not help.

[Jim Shepard]

Here's the back side. Only three wires and no selector for cylinder numbers.

 

[DJ194950]

1 hour ago, Jim Shepard said:

Here's the back side. Only three wires and no selector for cylinder numbers.

 

Remove cup and look inside. May actually be further inside of that if there is one, many do not.

If I remember correctly back before magnetic poles shifted to N. where it has been for many, many years- most 3 wires tachs (not all?)  used a seperate box that had to be used with them to operate.

Many stolen tachs back then where sold to the unknowing without the box as they where usually mounted behind the dash and unstolen.

DJ

[Don Coatney]

Old Sun Tachometers used a sending unit.

[JBNeal]

FYI I put a mini-tach on my old 4cyl Dakota that required the cup to be removed to access a toggle switch for 4, 6 or 8 cyl use...it had a 4th wire for its backlight

[Jim Shepard]

It's in a antique store near me. I think I'll pass on it. Thanks for all the info.