I can understand some owners not wanting to change the Morgan radiator spec from OE but in the 2014 on Classic series (and likely earlier) I wonder if they were aware the same plastic side tank rad was used on all three models from 4/4 to 3.7 Roadster despite the wide range of power outputs. I can only speak for the latter but can confirm that mine always sat at exactly the same temperature on gauge summer or winter once warmed up, which took little more than three miles or so.

After fitting my SiFab radiator it behaved exactly the same regarding gauge and warm up time. The difference was in radiator fan rarely coming on even in summer and then only at low speed. Previously the fan came on virtually every time I stopped to open the garage door. Another 3.7 Roadster owner found similar when he had a Mulfab aluminium radiator fitted, speaking volumes for the versatility of the engine cooling design of this model.

Richard

2018 Roadster 3.7
1966 Land Rover S2a 88
2024 Royal Enfield Guerrilla 450
1945 Guzzi Airone