Slow cranking starter

Hi (my first post so be kind!)
I have recently re-installed my 1.8 lump which was built by Racepower about 2 years ago. The problem i'm now having is after trying 2 different starter motors, i just wont seem to turn over fast enough to start up. I re-installed it recently because it needed some major work after a nasty head gasket fail at Brands. So i'm wondering if maybe after a head skim, that the starter is struggling with the higher compression? I've tried the standard mk1 starter and a larger one (from what i've been told a maestro van one. higher hearing apparantly). Or, could it be something as simple as a bad earth?
If it is lack of starter grunt, can anyone recommend a competition one they've used before?

Cheers!

run a jump lead from the battery earth to the block and try it,if its no better,it may be the live lead  :wink:
Bert

For some reason, after taking off the starter and putting it back on, seems to have a lot more juice

Not started yet, but soo close. Thanks for advice.

Try and earth the block to the
body