..........a 429CJ/SCJ dual entry oil pump?If so it would be interesting to see if it does the same thing.Maybe ford engineers addressed this issue with the next generation,but didn't see the payback for the FE since it was near the end of its life in cars.
I wasn't at the meetings at Ford Motor Co. and I didn't get the memo either, but my belief is that the 429CJ/SCJ dual entry pump was the first acknowledgement of another failed issue of the Gerotor pump as the speeds picked up, but also coupled to the introduction of the 1.1" versus the .875" length rotor & scroll desired for greater volume delivery due to the greater leakage area within this engine series even versus the FE.
One is often of the impression that the cavitation issue here is due to an insufficient pick-up tube delivery capacity, and although that often is a contributor, along with the previously discussed issue of the the by-pass retry effects, there is still more concern. The real "problem", as I see it anyway, with the Gerotor pump is the presents of 5-lobe scroll & 4-lobe rotor, in that the area being presented as each say chamber is presented to the inlet manifolding of the pump to be filled with fluid is to great as speed picks up for the time element allotted. At lower pump speeds it's O.K., the void presented by the rotor & scroll crosses the opening for the inlet plumbing system, oil flows in, but as the speed increases the time element decreases, the oil's mass precludes it's ability to fill the area so expediently and efficiently, and an additional pressure depression is realized within the pump body section it's self, this being something even less than that realized within the inlet system or pick-up tube. When the rotor & scroll was lengthen from the .875" to the 1.1" as supplied with the 385 series engines the engineers found the issue to be to great to ignore, and I can say from experience the 385 engines definitely display a tendency towards oil pressure loss at speed to a greater degree than even the FE.
With the "dual-inlet" the oil path thru the singular inlet flange is allowed access to both ends of the rotor & scroll chamber within the pump body, hence this effectively shortening the appeared length or distance the oil from either side is required to travel to fill and volume to pass in the allotted time, perhaps effectively doubling this filling rate, well probably not, but at least more efficiently all the same. And I believe this to be of good intention, but production of these have been discontinued with no mention of the change.
And then there is the problem with the fact that the chamber voids to be filled are presented in an interrupted or start-stop effect. This means that there isn't just a constant drawing of the oil from the sump, but rather the fluid must accelerate from a standstill to the velocity intended/required to fill the pump rotor & scroll chamber presented then this area is closed, the oil (with "bubbles"!) with perhaps inertia compresses against the blocked passage and even at times with synchronization reverses flow direction, then must be influenced with the next pump chamber void to reverse again! This is probably why one witnessed the "bubbles" exiting the P.U. tube submerged in the effective sump.
Scott.
And a fixed orifice bleed won't work as the pumps' delivery rate is not constant, even with R.P.M.s (yeah. I know it's a constant displacement unit), and the engines' bleed rates aren't either! So this requires a dynamic regulation function.
