What's the correct method of tightening the rocker arms?

W/ manifold on can I follow the 460s rocker arm 3 step assembly seq since firing order's Im trying to correctly assemble(tighten) the rocker arms on a 289. Ive followed chiltons (which says tighten to 17-23lbs when lifter is at the bottom or on the base of cam shaft. Had the intake manifold off when I did this. The top of the nuts on the studs at 23 lbs was approx.

Half inch down the stud and it seemed a bit tight looking at the spring compressed and all so I asked a friend who had me back them all out to where the rocker arms were just tight enough to where if I lifted on them the rods would respond, with no play as far as putting a feeler gauge between the arm and the top of the spring. When starting my comet after that the starter never seemed to really kick so after changing batteries and getting same results I looked at a old ford manual which didn't have the 289, but had the 302, which said the same thing as the chiltons.

I noticed the 460 had the same firing order and listed out a three step procedure, adjusting various intakes and exhausts with each step. We figured it would be the same if the firing ord weer was the same and since I already put the manifold back on, thought that would make it easier. So I did exactly what it said starting with the crankshaft on tdc at end of compression stroke and the adjustments thereon.

Torqued to 20 lbs the arms were back a half inch down the studs and feel tight. And now my battery with 14+ volts just clicks, so obviously I have it too tight, right? Thing is, I could swear when I disassembled them, the nuts were down that far, cause my regular socket wasn't working and had to get a deeper socket 5/8 to get the job done. 20 lbs torque brings the nuts just beyond the reach of the regular socket, so seems that would be correct. So why does it seem to be so tight or am I just looking at this wrong.