Do I have a faulty tach? It seems to work fine on the city streets but when I hit the highway it will do fine right at 2300 rpm for a bit then just slam up to 5k and stay there until the engine is off. Its got to be the tach right? The mechanic I bought it from is ordering me a different one during the meantime but this thing was new. Is an iequus 1000 rpm tach. I have a 327 .030 to 331, small cam, 700r4 stage 2 with shift kit. 4.10 rear