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4-108 Tachometer

jjgurley

New member
The tach on my 4-108 reads low at first, then seems to stabilize after a few minutes of warm up. My engine compartment is VERY restricted, and I haven't been able to find any sign of the sender yet. Any hints? The manual doesn't show the right side for the "new model" 4-108. The photos for earlier models show something on the block, but I can't access that area without hiring a midget.

Could someone describe where the sender might be, what it looks like, how many wires it has on it, etc? The gauge is electrical (as opposed to cable driven).
 
There are three options, a cable or generator fitted on the right side of the engine block behind and below the alternator. or it could be signaled from the "W" conextion on the alternator itself.
 
Does that mean there's an "adjustment" on the tach, at least for the "W" option? If that's the case, I guess I need a way to calibrate it?
 
If the guage has the "W" option it will normally (but not always) have a calibration screw on the rear, this type can become inacurate if the drive belt is worn or loose.
Sorry for delay in replying..
 
I looked harder, and found my tach is connected to the "R" terminal of my alternator. While checking the connector integrity, I bumped the 12V connection from the alternator to the batteries and it crumbled. After replacing the cable and lugs the tach seems to be working okay. Now the mystery is what happened to "bake" the connection? It was #4 and #8 wires from the alternator post to the house battery terminal. The connection nut was tight, so it looks like the crimps may have been sub-par?
 
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