When I bought the truck 2 weeks ago, the guage went was fine the whole way home (about 80 miles). Then I took the truck down to the wrecking yard to look for parts, and the guage was in the red the whole way. It ran fine and didn't ping, so I suspected a false reading and kept driving. The engine was in sad shape anyway and would be rebuilt within a week. I just put a new motor in the 73 c20, pretty mild motor built mainly for Towing, not going fast. its a 355 with flat top pistons, a Lunati 270/280 cam, headers, edelbrock intake with a Holley 750 carb and an HEI distributor. During the cam break in, I ran it for about 10 minutes at 2000rpms before the guage hit the red, then shut it off.....cam was broken in enough for me. I went to take it for a drive today and got about 2 miles away from the house and the guage kept climbing till it was pegged. The radiator is new, water pump, T-stat, hoses, heater core, fan clutch, everything. This disturbed me. I grabbed an Autometer Temp guage I had laying around and stuck the sending unit in the intake manifold and wired everything up. The Autometer guage reads 160 when the factory gauge reads half, and 180 when the factory guage reads "on fire". The strange part is that the factory guage, aside from being extremely inacurate, operated normally. I even bought a new borg warner sender for the factory gauge with the same results. The sender is unchanged. Could someone explain to my how a guage could fail this way?
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