940 Tachometer swap

Hi all.

I swap into my late 96 940 tachometer from 92 940, it has a little boost gauge (only for style), but I have a problem. On turbo tachometer idle RPM (and maybe others too) higher on 200-300 rpm. On idle I see 1000-1100 RPM on dash, that make me little crazy

How I replace tach - I just reinstall plate from my old non-turbo tach on turbo-tach mechanical part and plug vacuum hose.







How can I adjust tachometer?

I google it few days and found absolutely nothing.

Did you measure the actual idle RPM to see which tach was accurate?

Shifted said:

Did you measure the actual idle RPM to see which tach was accurate?

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Yes, ofcourse, old tach w/o boost gauge was accurate. New face - up to 200-300 rpm

cleanflametrap said:

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I don't know. Plate came from my old tach, where it work properly.

Bump?...