Originally Posted by Blown Camaro
Changed headers. Old ones were wrapped. New ones are painted. I have the sender with the capillary tube running under the #8 tube with about and inch of air gap. Rear of passenger cylinder head. Now when the cars idles the temp climbs from 180-210 in about 5 minutes. I am thinking heat soak. It never did this before. When I drive it drops back down to 180. When I turn the car off it pegs the gauge at 280! Anyone else have this issue with the mechanical gauge?
Haven't configured one as you describe, most common SBC Gen I set up I use is to come off the near center tap on the heads, passing above the header tubes.
I do find that that at idle the otherwise "normal" running temp will slowly climb this is just a function of air flow reduction across the radiator core without road speed to ram air flow through the core.
At shut down the temp will climb, but 280 seems high, my installtions usually see a climb to 220-230 which comes right down when the engine is fired up while still hot. Of course this is an event you don't see with an electric gauge as it and the electrical system is shut off with the engine.