Mine sets on the line perfect, what would represent zero. At idle it should read just an N'th above what would be 5.0 to 6.0 between the marks for 0 and 10. Just a lines width above what would represent '5'. Which would translate into about 600 rpm plus or minus 50-75 rpm or about 620 to about 650 rpm. The stop may be worn, I don't believe there's a pin.?? I'd have to look on mine, but it's dark and cold outside right at the moment.
01-05-2013 05:48 AM
OK, I just went out and started it, a 95 4.0. It was 27 outside, I started it and let it warm up, setting the fan on the second position of three until I got up to temp. It took about 10 minutes to get up to full temp at which point it was putting out good heat. I was tacking about 4.5 rpm fully warm, it was just under the imaginary #5 between zero and ten. It sounded like it was in its fully warm 'sweet spot' at idle, just right. And no.... my unit doesn't have a pin at the bottom of the tachometer sweep. I have 145K on the motor with a fresh oil change 10w30 and Rislone 'Zink' treatment.
01-05-2013 09:38 AM
Looks like ill be pulling the tach and cleaning some contacts. I'm thinking my idle is about 2-300 lower than what it's reading.