Grey engine operating temperature

[Fraze]

Advice wanted re grey engine water temperature. I have stock 138 cu in FB engine in my FC  everything seemed to be operating quite happily when I had the original radiator fitted however that developed terminal leaks so had to be discarded. I fitted a replacement radiator which I had, modern 2 row core and the car seemed to be running hot (not actually overheating) with that so Ihad the original rad recored with a 3 row core, and it is still not running as cool as with the original rad. I have fitted a temperature guage with the sender mounted on the head where the heater tap is usually fitted. At normal running, around town or on the freeway it usual registers about 90 deg C and when I stop at traffic lights it quickly shoots up to about 100 C . Once I get moving again it just as quickly drops back to 90 .  On the highway it will hold 90 until it hits a climb, even a slight  incline and it quickly goes to 100 or even a little more.
I have triple checked the ignition timing and run the water level about 40 to 50 mm below the cap, which is 7lb.
Question, do I have a problem or am I worrying about nothing?
Second question, has anyone made a fan shroud for one of these radiators?
All advice gratefully accepted.

[Harv]

Fraze,

100ºC is pretty hot for a grey. The original thermostat is designed to control to 71ºC, whilst the original idiot-light is set to come on at 217ºF (103ºC)

Is your idiot-light coming on (or flickering) under the high-load conditions, and hence confirming the gauge? Could be that you have a dodgy temperature gauge. One way to check it is to pull out the gauge sender, run an earth back to the block, then put the sender into some boiling water (a just-boiled coffee mug of water is close but drops temperature fast). It should read exactly 100ºC if the mug is close to boiling. A $5 thermometer from the pharmacy can make this check a lot more accurate, and will let you check the 70-100ºC range as the coffee mug cools.

The grey shouldn't need much more than the standard radiator and no extra shrouding - 3-core is more than enough.

Cheers,
Harv