(T) Oil pump gears question (anorak warning!)

Well as you guys would say, this deserves an 'anorak warning'

I took the sump off my Uno Turbo today, to remove all the orange gorilla snot and de-rust/paint the outside.

To get the sump off, it's much easier to unbolt the oil pump - so I did.

Having done this, it seemed rude not to take the oil pump apart and check for Day of the Triffids scenes within (waving tentacles related to the use of gorilla snot)...

I was bemused to see '128A 000' on the oil pump housing (so, the same part since 1969).

The gears have quite a discernible amount of backlash. I was surprised. I went to my parts collection and dug out an oil pump from a 128 Coupe. As I suspected, the gears have half the backlash, but are also slightly thicker - they have one less tooth. The older gears are helical-cut whereas the newer gears are straight-cut. See attached picture.

Question is, which is best?

I wondered if more teeth = more oil pressure (and we all want that). But, the gears with less clearance (backlash) would work better? Also the tooth surfaces are smoother in appearance. Maybe my Turbo's oil pump is rather worn from neglected oil changes (before I owned it, of course).

I'm tempted to use the 128 oil pump but with the (longer) relief valve spring from the Uno Turbo's oil pump. There is a difference in the length of the splines on the end of the driveshaft (the 128's is shorter because it shares the drivegear with the distributor). I don't think this would matter.

I know that I should really break out the feeler gauge blades and attempt to measure both pumps and compare with specs. But since there's a difference in design, I feel that it's fair to wonder which design is best.

Anyway, thanks for your time!

-Alex

gooday, rather use the same pump as the one that is in your engine, because the turbo will push more pressure than the other one because of the turbo. just use a feeler guage and measure the tooth 2 tooth clearance, and the tooth 2 body clearance and compare it to the workshop manual specs.

Alex, I must have a few turbo pumps around, your welcome to check them out