Rev counter

[Nick H]

91 comp 351 pcm

My rev counter appears to be reading exactly half what it should be, does anyone have any clues as to why ?

Thanks

Nick H

[dndsam]

Your tachometer is set for a 4 cylinder. Sometimes there are swsitches/knobs/screw on the back of the tachometer head that needs to be set for an 8 cylinder.

[Nick H]

thanks.

I took the gauge out and there is a switch on the rear to switch from 4 to 6 to 8 cyl. It was set to 8 so i switched it to 4 then back to 8 and hey presto it works fine.
Must have been a loose something ?