This post is via "dead-slow, dial-up, unreliable, dial-up" internet connection; so, no photo's or extensive dialog in response, please.  I also cannot access responses immediately, so, will wait until some time has passed to look for your opinions.

Which is the "better" oil pump: The georotor style, or the two-gear style.  Why do you think so?  Reasons?

Regards,   JLB

55 Ford Crown Victoria Steel Top

JLB;

I like the georotor type pumps because they sell kits to rebuild them. They were used in the later Y Blocks and in trucks which make me think that the engineers thought these were a better design. I am pretty sure you have to buy a new steel gear driven pump if it goes bad. I don't recall seeing rebuild kits for these type pumps. I also have been told, but have no proof, that the georotor pumps provide a more steady oil flow. You will probably get different opinions on this, but that's my 2 cents worth.


Rono

  Ron Lane,  Meridian, ID

For street use, either is perfect.
For high rpm use, the gerotor has an edge, less cavitation and spark scatter.



Lawrenceville, GA

 I’ve posted this information in the past but rather than reposting the link, I’ll repeat the information with some updates.
 
The aluminum oil pump is typically the gerotor (or gerorotor) style while the iron oil pump is the older spur-gear style.  The aftermarket actually made the gerotor style in iron for awhile as I still come across some of these on core engines on occasion.   Although both styles of pumps are rated at the same volume, my own preference is towards the gerotor style as they have a smoother pumping action with less pressure pulsing taking place.  The gerotor style has fewer issues regarding cavitation when compared to the gear style and part of this has to do with the aforementioned pulsing that takes place.  It’s not unusual to actually hear the clicking of the gears in the older style spur-gear pump which can be disconcerting is you don’t realize what it is.  Melling still offers a rebuild kit for the gerotor style but I’m not aware of any companies producing a new from scratch gerorotor pump for the Y at this point in time.  The Melling kit part number for the gerotor pumps is K-56.
 
But back to design differences.  The gerotor pump has four lobes on the drive which takes roughly 180° of crankshaft rotation to fill the pumping chamber.  The spur-gear pump for the Y has a 14 tooth configuration which effectively has only 51 degrees to accomplish the same thing.  Because the gerotor pump has roughly 3½ times the work time to fill its chamber, the oil is allowed to ramp much more smoothly into the pump chamber and likewise shut off much more slowly as the cycle is completed.  This smoother action is less likely to pull gas or air out of the entering fluid stream than the same volume rate spur-gear pump which is trying to fill itself 3½ times faster.  At 6000 rpms, the spur-gear pump is trying to fill itself 42,000 times per minute while the gerotor pump is trying to fill itself at 12,000 times per minute.  Because the gerotor pump is filling itself in fewer cycles or pumping actions, less heat is being generated into the oil and hence a cooler oil temperature is being transmitted to the bearings.  This results in potentially less oil degradation using the same oil change intervals.

Lorena, Texas (South of Waco)

JLB.  Rono and Charlie have given you good info.  The Forum Archive has more info to support what these two have shared with you.  IF you're building a high rpm engine, go with the georotor.  For normal street and highway use, either is suitable.  Ford began using the rotor style in the y-block in late '56 model year and continued to use them through the end of production in '64. 


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

Folks,

Thanks much for the information.  I'll use the gear pump for my "temporary" street engine 292 (bored to 297) to replace my dying original 272 in the Crown; and, save the georotor pump for the 312 which will be "built-up", then.

The 292 job is only a "refreshment" anyway (not a complete rebuild), in helping me enjoy some drive time while working on the 312 (which may take another year or two!).

I haven't been able to visit here much since retirement because of this awful dial-up -- only takes 1/2 hr or so to log-on & get to the forums!  My old office desk used to have 100 Meg to the desk; quite a change & very frustrating most of the time.

.Regards, JLB

55 Ford Crown Victoria Steel Top