This is for the guys running a belt driven external oil pump on their slants.
I see that most guys run the single stage pumps. Most of the pumps I have seen look modular. Is it generally possible to change a multi-stage pump to a single stage?
Is there a recommended pulley ratio to use when driving the pump?
Do they have a bypass to regulate max oil pressure?
I don't currently have any plans to switch to an external pump, but it is something I keep on the back burner, so to speak.

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-MattMan
LEANED & MEAN

They do have an internal relief that is easily adjustable for peak pressure.

I asked the engine builder that I know who works with the 3 & 4 stage dry sump pumps if the suction sections of those pumps could be removed and then just have a single stage pump. He said that he thought that they could but he wasn't sure. He'd need to take a closer look at the pump and see for sure. It never went any further than that for me.

I can count the teeth on my set up if you want to know the pulleys I'm using? 13 & 36 sticks in my head but I'll check for sure.

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

I am just gathering information at the moment, in case I ever go that route. I am hoping that DD's idea with the revised oil pump drive gear bears fruit. I have no plans to change anything in the forseeable future. If I see a good deal on one of the belt driven pumps, I might pick one up.

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-MattMan
LEANED & MEAN

It'll depend on the manufacturer/design. A lot of multi-stage pumps are 'modular' and they can be stacked up or down to add or remove stages. Some can't.

But I'm assuming you are asking because you want to buy a multi-stage pump cheap and use it as a single. Otherwise, just buy a single stage pump and be done with it. I haven't bought one yet, but I'll be buying a Peterson 04-1422 soon for a V8 I'm working on.

As noted, they have easily adjustable regulators.

As a rule of thumb, adjust your pulleys so the pump is spinning no more than 5000RPM when your engine is a full RPM. Similarly, it should spin no less than 3500RPM when your engine is at full RPM. The low side limit can be relaxed if your oil pressure gauge tells you it's OK.