Well I had a tach cable installed on my 1979 140 horse Merc. Well wonder of all wonders not only does the tach work but now the amp gauge does too! Only problem is that at anything over roughly 2000 rpm the gauge goes right over to 16. Now in a car this would mean boiling the battery. If I turn on the nav lights it will drop it a bit at lower revs but at about 2500 up it just stays topped out on the gauge. Do these things have a voltage regulator or is it just the higher the rev the higher the charge?
<br /><br />-W