QUESTION-  I just got my recently restored TR3A back on the road and it overheats easily on hills and driving on warm days.  I checked everything I can think of but the car still overheats easily.

ANSWER - Many people who restore their TR3A discover that it tends to overheat more easily after the restoration than before.  Then they check and recheck everything they did paying particular attention to the radiator bypass and thermostat.  Some possibly swap in a different water pump and recore their radiators to no avail.

The biggest single cause of overheating problems I have found so far in a restored TR3A is the available replacement grille. They seem to use the same amount of metal in the replacement grille and originals, but do not fold the 'V's as deeply in the replacement grills. The result less area for air to flow through and more edge interference to the air flow.

The after market grill has holes 7.2 cm (2.83 inches) by 1.3 cm (.51 inches) for a 9.36 cm^2 (1.44 square inch) opening.

The factory grill has holes 7.7 cm (3.03 inches) by 1.6 cm (0.63 inches) for a 12.32 cm^2 (1.91 square inch) opening, providing 24% more area for air to flow to the radiator.

Aftermarket grille on top and factory original on bottom. The original has 24% more area for air to flow to the radiator

The factory race cars had grilles modified with deeper metal folds allowing more air to pass through the stock factory grille.
Another strategy might be to crimp the horizontal sections of the grille for a wider opening.
Also note the airflow opening below the grille that provides cooling air to the part of the radiator that fits below the front apron deck.

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