Just to clarify:
Edelbrock pump #8841 (satin), #8846 (polished), #88413 (black painted), & #88414 (Endura-Shine) are pumps designed to fit the '65-'69 timing covers, right-hand inlet, "WITH BACK-PLATE.
Edelbrock pump #8842 (satin), & #8847 (polished) are pumps designed to fit the earlier timing covers, right-hand inlet, "WITHOUT BACK-PLATE" (those timing covers with oil-fill, breather tubes or plugged orifice for such present)
I'm not so sure that these pumps actually pump more "efficiently", whether that be by actual flow volume or through potential pressure production, that over the standard O.E.M. units, as though I haven't actually performed flow test comparisons, but after all, they seem to exhibit the standard stamped steel impellers and as referenced previously, Ford Motor Co. intentionally reduced the pumping capability of the standard passenger car units with fewer impeller blades in certain applications; those where they anticipated they'd be turning faster anyway.
We utilized the O.E.M. die-cast aluminum housing pumps in some of our endurance racing applications as they do present the lightest weight of any, but this housing did periodically exhibit failures of the nose section extension of cracking/fracturing or expanding/wallowing out of the bearing bore and losing retention of the shaft bearings.
We did convert these applications over to aftermarket pumps (Weiand or Edelbrock) if only for the heavier castings which solved the issue of housing failures, but really did not realize any significant differences in pumping function.
Same with the use of the cast impellers vs the stamped steel units. though I prefer the cast units for durability, but if one doesn't over-speed/over-pressurize with stamped pieces then there generally isn't any problem with them.
Scott.
