Checking Voltages on Phase Converter

I have a 2HP Sheldon Variable Speed Lathe. I have a 7.5 HP UNTUNED phase converter that I built using Jerry Marte's design using a solid
state relay to switch the third leg in. The lathe just does not seem to have the power that it should. I then read somewhere that if your RPC is not tuned then you may only be getting 80% of the available HP that you would get if it was tuned.
Should the voltages be checked with the lathe motor running unloaded? If so where should I check the voltages? Should I check them in the lathe's electrical box where the cord from the phase converter meets with the motor terminals for the lathe? I have a good digital voltmeter and also a clamp on amp meter although I am not really sure how to use the latter or where to attach it??? I am aware that I should use approximately 12uf per motor HP for the run capacitors.
Also, my panel box is full and I do not have any room for run capacitors in the box. Can I get another box and put them in there and run the appropriate wire to them? Any help greatly appreciated. Thanks, Steve
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I am aware that I should use approximately 12uf per motor HP for the run capacitors.

33 uF per idler motor HP for a simple (A-B cap only) type ... the same for a balanced (A-B and C-B caps) type, with 60 percent A-B and 40 percent C-B.
The starting cap should be applied across those phases which has the larger run cap (usually A-B).
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