Things I've learned:
The 40 degree mark is 62 degrees of timing on a Tekin 17.5, which means 17 amps when free spinning.
I dialed it back to 45 degrees and only 3 amps free spinning amp draw on the checker. Maybe that's why that thing was such a dog.
My LRP X20 17.5 is actually advanced some 5 degrees past the claimed number on the insert, but it had one of the least variance between the three poles. Even so, it was drawing less than 2 amps at 40 degrees advance showing on the meter.
All timing is not created equal, and older motors have much less timing built into them than new ones. My old Trinity Duo 17.5 was timed at 45 degrees with the endbell cranked to the stop, but spun pretty high and only drew 2 amps on the checker. Setting my Orca RX3 to 45 degrees drew over 6 amps, and it didn't seem happy with it. The Orca RX3 seems to want less than 40 degrees.
On the other end of the spectrum, my Team Powers 17.5 only drew 6 amps with 60 degrees of advance. It seems the wind and core construction of the motor counts for more than I thought.
Modified motors get so much more out of a given amp draw. 2 amps of draw on my 4 turn gives me over 35,000 rpm.
Check your bearings. One of mine was gummed up with track detritus, and you never would have guessed by looking at it.