because i have heard that if you swap a ..... into a ....... the tach reading are usually off by 2-300 rpm , because if your tach only goes to 8 and you can realisticly go to 9 it must be off by a little bit

 

I have never heard of a 2-300 rpm difference. My understanding is that the tach on your cluster gets a reading from a wire in the distributor plug, so it shouldn't be off. If you are talking about timing, I am sure there are differences between the stock motor and your B16.

As for the motor's capabilities compared to what is listed on your tach, yea, that is understood. Especially if you have a stock cluster with a different motor and ECU. Technically, the ECU controls the rev limiter, not the motor or the cluster.

 

yeah i have a pr3-003 ecu (90 xsi integra) and my b16 , i still have the stock 1991 si cluster, could that make it read a little differently, i idle at around 900 and its nice and smooth sounding