RPM clueless

I know someone at ebay that could help you be extremely accurate.

[ame="http://www.ebay.com/itm/VDO-Chrome-8-000-rpm-Tachometer-Vintage-/221569191406?pt=Motors_Car_Truck_Parts_Accessories&hash=item33968d8dee&vxp=mtr"]VDO Chrome 8 000 RPM Tachometer Vintage | eBay[/ame]