There are a couple of "fixes" for the MGB heater. The 7 Enterprises fan
may help, I have gotten mixed reviews, some say only more noise, others
love it. My 1st fix was to seal about 50 small air leaks, especially one
from the inner fender to the under dash.
You should be running a 190` thermostat, or 195`. Flush the heater core,
check the heater control cable to see that the valve is opening
completely, most do not.
Moving along, I salvaged 1 of the only 2 worthwhile parts from a TR7,
the heater fan from an A/C car. This differs from the non-A/C car in
that the motor is more powerful, & is mounted in a large flat plate. The
front of your heater box can be cut, enlarging the fan opening, & the
TR7 A/C fan, with plate, screwed onto the remaining cover. This takes a
little planning to get the location correct, allow about an hour.
For a re-circulating heating system, later cars with fresh air vents in
the dash, cover the fresh air intake on the cowl, open the dash vents.
This will make cabin air the supply to the heater motor instead of
outside, colder air. .Interior air will move into the vents instead of
coming out the vents.
If none of this helps, buy a car from one of the listers who crows about
how hot his feet get at 30` below in his MG with the top down. If no one
has yet made this claim (I am on the digest, so word comes slow),
someone surely will.
Vintage Air HEAT & A/C in my MGBGTV8
(the other solution to the heater problem)
p.s. the other worthwhile TR7 part is the armrest, direct screw-in for
later B's, dosen't come apart, wide enough for an adult arm.