Dude, check the tach for it to be set for a 4 cyl. Most aftermarket tachs have a button (in the bottom back) you can select, 4, 6 or 8 cylinders. If you have it set for a 6 or 8 cylinder, the signal frequency will be lower, thus reading a lower RPM than you're actually running. Hell, if it's set on 8 cylinders, you're actually shifting at 4800+RPM. If it doesn't have a button, then most likely your tach is meant for 8 cylinder cars. Check the button and let us know what happens so we can help you more if you need it.
1987 GLS - Genesis...
1988 XR5 - Will Always Live...
1993 HO XR5i - 3rd Time's a Charm...
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