An excellent article about a subject that many of us who use their MGB’s during the winter months consider. Getting the heater out and then back in again is a job and a half so whilst i had mine out last year i put in an uprated matrix – and what a difference.
More info at:-
https://www.1020mg.org.uk/2014/12/mg-tech-uprating-an-mgb-heater-system/
NB. Another item to check is the heater valve that can get blocked.
MGB tips mods and maintenance 