I've seen a couple of replys to your origional question and want to ad a
caution. Someone said that water is the best coolant; not so, use a proper
50/50 solution of antifreeze. It will offer better cooling and protect your
system from corrosion. This should be changed at least every 3 years for the
same reason. I do mine more often. The other suggestions re. your
overheating seem on target.
]I have the Weber conversion on my '76 MGB, it was done by a PO. I bought
the Haynes carb book for MGs and set it up according to the book when I first
began driving it. I have enjoyed many trouble free miles since. That
dosen't mean that the origional set up wasn't as good or better, I just don't
know but I am quite satisfied with this.