Wow, who hasnt experienced this problem? From soup to nuts on the wiring from battery to starter and every ground involved for about 10 years I have fought this problem, one or another connection making an improvement for a while. Last week I realized one lace I had not checked was where the ground strap connectors to the lead (?) connector that goes over the battery terminal. Took it apart, strap is about 20 strands of bell wire twisted together, not one strand was copper colored--all coroded. Spread strands apart, put wire brush in drill, cleaned it all up, put it together and have never heard a Healey starter turn that fast.
Jay Glass
'65 3000