Whats the difference between the cast Iron pump and the Aluminum pump? I think its the gear versus rotor deal but not sure which is which. Or which is preferred? Chuck in NH

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

The aluminum pump to which you refer is the gerotor (or gerorotor) style while the iron pump is the older spur-gear style.  The aftermarket actually made the gerotor style in iron for awhile as I’m still using up some of the new old stock of these.   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 aformentioned 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.

 

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 rated spur-gear pump which is trying to fill itself 3½ times faster.  At 6000 rpm, 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 being transmitted to the bearings.  And potentially less oil degradation using the same oil change intervals.  And it’s way early in the morning to be thinking this hard.

Lorena, Texas (South of Waco)

THANKS, Ted. I thought that I'd read a more complete explanation to Shooter's question.

Again, in digging in the archive, some threads were listed, but no longer accessible. OUCH!

Is anyone else finding this since the software update?

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

When the forums moved to the new server, the link addresses also changed. If you come across a link that attempts to go to the now defunct old forum, it can be edited within the browser bar so the post can be accessed at the new server.

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The old address looks like this: http://www.y-blocksforever.com/forums/Topic38818-3-1.aspx
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By editing the address so the“forums” portion is moved to the front of the link and the “www” is removed, many of the old links can be accessed. Also remove the suffix numbers from the end of the link after the main topic number.  Here’s the edited link:

http://forums.y-blocksforever.com/Topic38818.aspx

Lorena, Texas (South of Waco)