marv h.

Thank you first generation guys for the help on getting my Dad set up with a tach. Now I need to ask you another question. Dads pickup is a 91and1/2, can you tell me what rpm it should be turning at an idle? It sounds like it is idleing a little slow. His CPL tag is missing. It is a 5 speed converted to an NV-4500. If you could help I would appreciate it.
Thanks, Marv.

G1625S

I set mine @825 in the winter and 750 in the summer. It's really personal preferance. Some of the industrial apps idle at 500, but that would likely rattle your pops' doors off anything above 850 is just wasting fuel, imo.
greg

wannadiesel

I like 850 RPM. The FSM says 750 RPM, but the mirrors shake too much there.

jeepsuck

how do you change your idle speed? mine is at about 600 and sometimes my whole head shakes with the truck.

marv h.

Thankyou very much guys, I will let him know.

P. S. Do you know of any tricks to callibrate the tachometer to read the correct rpm?
Thanks Marv.

AlK

jeepsuck,
how do you change your idle speed?

The idle screw is located (looking from the front of the truck) on the left side of the injection pump. It is a bit of a pain to get at. The lock nut has to be loosened before you can turn the screw.

wannadiesel

A lot of diesel shops have an optical tach. They stick a piece of reflective tape on the damper and point the tach at it.

The other thing to do is calibrate it by road speed in direct drive. Takes a little math, but it's pretty accurate.

Chrisreyn

hmmm... Mines idles at start up at araound 600 and when warm at around 5....
Not shaking badly,, but is this hurting anything to have it idleing this low?

Blowndodge

probably not, but your brake boost or PS might be a little sluggish! I've heard others have a problem with no brakes at times. Mines at 700 with the air conditioner on.