Water Temperatures

[KFH]

I have an FB head on my grey.  From the outlet on the back of the block I run a Smiths temperature gauge and from the front outlet I have the "idiot " temperature light connected. The gauge has recently been repaired and calibrated. A while ago I tested the temperature light switch and found that it switched on at 210 degrees.  When driving the temperature sits at 180 degrees or a little below.  I find that the "idiot" light comes on when the temp gauge reads around 190 - 200 degrees. The car never boils or use any water.  What temperature difference would be expected between the two points on the head.

[Harv]

Lots of temp difference across the head, with the front being cooler due to the standard water flow favouring #1 cylinder. The “improved cooling” head gaskets even this out. Robs thread on the gaskets has some good temp measurements that he took with temporary thermocouples (cool science).

Cheers,
Harv

[Fraze]

Temp variations accross the head are very interesting. I have an FB head on my FC. originally I hooked my temp guage to the front port on the head and got some alarming readings. the engine always seemed to run at 90 C + and while cruising even a small hill would send the temp up dramatically only to drop back when finished climbing. Often on a hot day the temp would exceed 100C. The idiot light never came on, I did test it and it was OK. I figured I had a problem so with a hot engine I checked (surface) temperatures with a laser temperature reader. I found the the temperature at the front of the head was by far the hottest spot! the back of the head was significantly cooler and the thermostat housing was cooler again. I would have thought that the thermo housing would be hottest as that is where the water exits to the radiator. Anyway i obtained a EJ thermostat housing which has a tapping for a water pipe and fitted the Temp guage sender there. I now have the heater outlet coming off the front of the head and returning to the port at the water pump. ALL GOOD NOW. The guage doesn't fluctuate like it used toand sits on a fairly steady 80 to 82 C. It only gets hot ( maybe up to 90C) when It sits idling as at a traffic light, but quickly drops back to 80C when we get moving. My engine has the original type head gasket. High ambient temperatures, say above 30 C increase my engine running  temps by maybe 2 to 5 C. Hope this helps, cheers, Fraze.

[KFH]

Thanks Harv and Fraze. It seem like I do not have any problem.  I'll reroute the heater hose to the front port and put the idiot light in the thermostat housing and hopefully things should be good.

Keith