1990 gauge swap...tach not reading correctly

[350cjmass]

Hello everyone,

I've owned my Comanche for roughly 6 months & have found this forum to be a great resource. Just wondering if anyone has replaced the "idiot-light" cluster with an actual gauge cluster; only to find the tach is way off?

I've got a 4.0 & installed a "unknown" cluster... at idle the truck is reading MAYBE 0-100?? Rpm. It's working properly, adjusts with engine speed; but is reading rather low.

I dissassmbled the cluster and found the adjustment screw, but can't find if I'll need to replace the resistor if in fact my cluster came from a 4-banger??

Will adjusting the potentiometer screw correct my issue? Or should i look to replace the resistor/get another tach?

Thanks in advance for any and all help. :bowdown:

[jimoshel]

Try adjusting the pot first. That's why it's there.

[350cjmass]

Thanks for the good words....I'll hook up a "real" tach tomorrow and let y'all know. I just didn't want to screw with it too much in case it was perfectly setup for a 4.

I plan to start posting a build soon; just about done with my "Spotweld-Nightmare"! Replacing the entire floor & upgrading every single suspension/steering componebt has been quite fun..lol...Not even close to my CJ or XJ hours yet; BUT, still got plenty to go:-)

Thanks again,

Mike

[Geonovast]

If the tach was set for a 4, and you have it on a 6, it would actually read high, not low. The needle was probably fubared at some point. You'll probably be alright just swapping out the tach.