Chosing Oil Pump for 2.4

[Swallowtail]

Hi guys,

I know this topic has been discussed a lot and I think I read most of the corresponding threads.

In my case I will be rebuilding my ’73 911t engine close to stock but with higher compression (9.5:1) P&C.

I finished the tear down yesterday and found the original 3 rib Mg pump. I’m planning to run the oil bypass mod and hydraulic tensioners so from what I read anything with 4 ribs or later will be fine.

I’ve been browsing the offers for used pumps and found that there are a lot more 964 than Carrera pumps for sale. Right now I can decide between a 964 pump and a 3.2 (911 107 105 1R) pump, for about the same price.

My questions:
- I believe the 964 pump is made from Mg and the 3.2 pump from Al. I read that the Mg housings might develop problems over time. Is this true and reason enough to chose the 3.2 pump?
- Is it generally a bad idea to buy a used pump or is it possible to assert its health with typical home tools?

Thanks,
Andy