Used Oil Pump Opinion Sought

[wwhalenc]

How foolish would I be to swap out my known good 2.7 oil pump for a used 90K SC pump from a fellow pelicanite? Thanks in advance for your 2c.

[dtw]

Same pump with an aluminum housing on the SC, if I'm not mistaken...assuming you have the 4-rib 2.7 pump (magnesium housing). Don't think there's any change in flow/pressure, but SC pumps are newer and seem to command a few more bucks in the used market. Having just faced this same decision, I kept my good 2.7 pump and sold the 3.0 pump I had on the shelf...

[wwhalenc]

What can I say? New pumps are pretty pricey. My motor was from a '74 911. I haven't yet cracked the case (or really looked in there even), but I gather the pump is the earlier 3 rib (and the case will need the oil-bypass mod to employ a later pump). My thought was that it's worth doing even if with a used SC pump.

The question was more about deciding if employing a used pump is foolish in general. I guess it's pretty common?

[dtw]

Very common. Do your oil bypass mod and upgrade to a good used 4-rib 2.7 or 3.0 pump.

[Henry Schmidt]

The SC pump is a better choice in that the aluminum housing has a lower expansion coefficient. This means that the pump tolerances stay more consistent when things get hot.
Magnesium 908, 4 rib pumps are an improvement but the aluminum housing is the icing on the cake. Lower expansion rates are also the reason the turbo pump has a cast iron scavenge cell. There are ways to make these and turbo pump flow about 15% better.
Many shops will do this modification for you. Supertec is one.

[jaybird840]

Ok, so somebody dumb it down for me.... Will my 3 rib pump in good condition work OK on a 2.7RS build that won't see anything more than aggressive street driving? Oil bypass mod is being done on the case as we speak.... Thanks!

[Henry Schmidt]

Low oil pressure at idle is a chronic problem with mag case 2.7s. The larger pressure cell of the 4 rib pump is designed to create more flow at all rpm ranges to prevent low rpm oil pressure.
If you must use the old pump, get it flow modified and use cam feed line restricters.

[dtw]

What Henry said. But there's no reason to use a 3-rib pump when good used SC units are available for 200 or less.

You can make some of that $ back by selling your 3-rib pump to Roy @ MotorMeister.

[wwhalenc]

I'll take the first known good pump offered for 200 or less!

[dtw]

There was one on the classifieds yesterday at that price.

[dion914-6]

Originally Posted by wwhalenc

I'll take the first known good pump offered for 200 or less!

Look around....bought a good used one on eBay last year for $110, but if you will give me 2 bills for it......

D