Next, I put a straight edge on the gears to check alignment of the dots. This becomes TDC #4. The cam gear is in the 2 o'clock position as shown, and the dots are perfectly aligned.
Then, I rotated the engine 360 degrees, to TDC #1. I pushed in on the tensioner side of the chain to take out any extra slack. The crankshaft is at TDC and the cam is in the 8 o'clock position.
Then, I installed an oil pump that is representative of the majority of oil pumps on my bench - this pump shows 32 degrees alignment in the first post in this thread.
The pump does not align with the 48 degree template.
It does align with the 32 degree template.
Note that in the photos of the timing chain, I haven't pressed the gears all the way onto the shafts. This is so that I can remove them more easily (see my other post about seeking a good puller). As a result, the cam will tend to sit too far back in the block since the gear is not pulling it to the front - this affects oil pump alignment. In order to get an accurate measurement of the slot angle, I am gently preloading the cam towards the front of the block to remove any excess end play. This will be very close to the normal running condition.
So, where does this leave us?
We know cam timing on my motor is correct, because I measured it according to the method in the WSM, using tappet lift in lieu of valve lift and compensating for the rocker arm ratio of 1.4.
We know that chain slack does not significantly affect cam timing (or cause misalignment of the dots) because the effect is so small (at least on a new chain or one in good condition).
We know that the majority of pumps in my shop (4 out of 5) result in a 32 degree angle of the drive slot @ TDC #1. One pump (purchased in 2017 from Sunbeam Specialties) has a different slot offset and yields the desired 48 degrees. By the way, if I rotate the motor to TDC #4, and THEN install the pumps, the the situation is suddenly reversed - 4 out of 5 pumps yield 48 degrees and one pump yields 32 degrees. So not all pumps are created equal and that may explain why folks get different results. Amusingly, most of my 1725 pumps that have been harvested from old motors (some not running in 20+ years, so these are old pumps) have different casting marks and part numbers. They all say Hoburn Eaton but I have no idea if they are original or copy-cats. I'm not surprised that there is some variation in pumps - some of them may have even been intended for the Iranian Paykan (I'd love to see a workshop manual for that car!).
I built a second motor to show that it has the same problem - the majority of oil pumps in my shop show a 32 degree angle when the cams are properly timed and the pump is installed when the motor is set to TDC #1. I think this double-confirms that the cam timing for the first motor is correct, since i get exactly the same results on a second motor in which I have shown precise alignment of the cam dots with a straight edge.
I think Rootes made a mistake when they put the 47-49 degree number in the WSM for the 1725. I think they forgot to change the number when they changed the number of teeth on the gears from 12 to 11 teeth. The 47-49 degree figure is only valid for a 12 tooth cam/pump combination. Rootes removed the figure from the Hunter manual and I think by that time they had realized their mistake. It also seems that some oil pumps (such as the ones Sunbeam Specialties is selling) have the slot in a slightly different position in order to correct the situation, so depending on what oil pump you have on hand you might be able to achieve the 48 degree rotation, or not. On the 1592 (and maybe earlier motors?) there is no problem - the symmetric nature of the drive gears means that you can always achieve a 48 degree angle regardless of TDC #1 or #4.