tachometer calibration?

[bigrusty]

Hey, i couldnt really find anything in other treads, so ill just start a new one. I recently got on of these tachs: http://shparts.com/92%20dually%20cluster%20002.jpg

i think it works and all, but at my idle its telling me 2500 RPM o.O or even 4000 sometimes. I know for a fact that it does not idle that high, and im wondering if the old cluster, the one without the tach is calibrated differently, or if i got a dud.



http://www.youtube.com/watch?v=VwpAo-Oay1A
Did anyone else have these problems when they did a cluster swap? This 3500^ with the same engine as me idles at ~400-600, so i'm way out of wack when it comes to this cluster.

Thanks in advance.

[bigrusty]

heres a pick of idle rpm
http://a7.sphotos.ak.fbcdn.net/hphotos-ak-snc6/169635_4242469748890_622520941_o.jpg

[TalkingHead]

Did you swap a cluster like yours, but w/o a tach for one of the same style, but with a tach?

What did the donor Cluster come from? I believe if you mix and match clusters between six and eight cylinder trucks the tach will be wrong.

Literally yesterday, I just swapped in gauges like these in place of some of the moonies (88-90) I had. I've been having random issues with my speedo jumping really quickly, but can't seem to ascertain why.

[bigrusty]

Yep, it was from a 93 suburban i believe could be wong it was cut up at a scrap yard. For the speedo jumping read this from a camaro thread:
Try This

"I work on electronic equipment at work a lot. I have not experienced the problem you describe but I would suggest that the first thing you should probably do is be dang sure that the contacts on both the cluster and the car are clean. What you describe could be the result of the tach getting erroneous signals through bad contact... Sometimes those contacts look clean but there is some accumulation of oil.dust etc that is just bad enough to cause a poor contact.

Worth a try before you spend any money...

Speedy
__________________
Speedgraphic
'90 RS Vert
New Paint, Top, Interior, Rims, Tires. IROC Swaybars, Alston SFC's, Billet Aluminum LCA's, Panhard rod and STB by Edelbrok. Hedman headers, Carsound CAT and Banks Catback. Restored close to stock. Installing XM Radio was one of the best things I ever did!

http://www.thirdgen.org/techboard/electronics/271896-how-hell-do-you.html
"It's hard to slow down, when you were born to run.""

My old tach, except diesel: http://images.gtcarlot.com/pictures/41288164.jpg