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Under the radar
Join Date: May 2007
Location: Fortuna, CA. On the Lost Coast near the Emerald Triangle
Posts: 7,129
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OK, after doing some more reading, Ultimate Oil Pressure Relief Valve Thread ,apparently the spring is SUPPOSED to be 86mm, not 88 like I thought.
I thought I saw 88mm, but the 8 was really a 5 I guess, on the pixelated printout I have. So the next question, is 89mm to much? Since I ended up shimming 3mm, will that be a problem?
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Gordon ___________________________________ '71 911 Coupe 3,0L outlawed #56 PCA Redwood Region, GGR, NASA, Speed SF Trackrash's Garage :: My Garage Last edited by Trackrash; 09-30-2017 at 12:37 PM.. |
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09-29-2017, 04:24 PM
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Will check the length of mine tomorrow... |
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09-29-2017, 04:53 PM
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Under the radar
Join Date: May 2007
Location: Fortuna, CA. On the Lost Coast near the Emerald Triangle
Posts: 7,129
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Update 2.0
OK, now armed with the correct specs, I decided to change from a 3mm shim (two washers), to one washer which is a 1,5mm shim.
The results seem to have me where I want to be. Still there is a hesitation in the oil pressure's increase above 60psi. I am getting 75psi at 6K rpm when hot, so I'm going to call it good. Still the question remains. Why does the oil pressure increase rapidly up to 60psi and slowly after that? The only thing that would make sense would be the piston squirters opening at that point.
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Gordon ___________________________________ '71 911 Coupe 3,0L outlawed #56 PCA Redwood Region, GGR, NASA, Speed SF Trackrash's Garage :: My Garage |
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09-30-2017, 12:44 PM
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Once again, stock piston squirters open up at FAR lower pressures than Porsche says they do. My test shows they can open with as little as 20 PSI.
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09-30-2017, 12:49 PM
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Well, so far found 1 stuck squirter... its the one that cools the cylinder with the most carbon build up... Is that a typical result?
Also, disassembled my oil pump. Its the iron 930 one. No scoring, impellers look great, there is some backlash between the gears, not sure if there is a measurement for this... But found one odd thing, I don't think I have seen mentioned before... On the intake, there are 2 small impellers not one large one. Ok, not sure why, but thats what porsche did. The odd think is the impellers on each shaft don't line up perfectly, they are about 1/2mm-1mm off on the keyed shaft. Meaning, on the same shaft, the top and bottom intake impellers are slightly "off" and not perfectly aligned to each other... Is that intentional? Its not like its loose, they are machined that way onto the keyway... Normal? Pic attached... 
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09-30-2017, 01:53 PM
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^ did you mark the mating surfaces between them? Because they need to touch on the same teeth as you took them out.
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09-30-2017, 02:29 PM
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Quote:
But take a close look at the pic...the teeth on each shaft don't align??? It's off 1/2 a spline... This is how it was before disassembly... I would think this would cause pressure loss at the joint line??? Is that normal? Found other pic on here and non had a misalignment... The gears can't be aligned, this is how they are pressed onto the shaft... Is that an intentional design feature? Last edited by bpu699; 09-30-2017 at 02:52 PM.. |
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09-30-2017, 02:48 PM
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Not an expert on oil pumps by any means but my guess is that it is designed that way to provide a little clearance and gap for the oil to flow through.
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09-30-2017, 04:51 PM
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Ok, this is odd...
Found more pics of 930 gears on the net... For example... https://www.flickr.com/photos/thewansinks/5229725351/ See how the profiles of the 2 gears on the same shaft are perfectly inline? Well, mine are off by half the thickness of the spur gear... Will look at it tomorrow. Not sure if the gears are symmetrical or not... The gear only fits on the woodruff key one way, it's not like you can adjust it to align... This is on the scavenge side, so probably doesn't make a difference? Clearly, car ran fine for 60k miles with this... |
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09-30-2017, 06:24 PM
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on all the oil pumps I have disassembled they are aligned. Others can give there experience.
thanks, john |
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09-30-2017, 09:27 PM
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Join Date: Sep 2015
Location: Costa Rica and Pennsylvania U.S.
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oil 5 bar
Crankcase alignment is critical to proper oil pressure.Bolt the halves together and check with a bore gauge.When the case halves are machined and the bore realigned there are no questions.That is the 1st step when you freshen a motor.Fred
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10-01-2017, 04:21 AM
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Quote:
Aluminum cases don't get bored, only magnesium as I understand it... Will probably send the oil pump off to Henry at supertech to check out... Want to do this once, and do it right... Rods are at ollies, bearings getting coated at hm Elliot, heads with cgarr... Have the AA rod bearings, and supertech head studs... Down the slippery slope I go  Bo |
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10-01-2017, 07:51 AM
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Location: UK
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It may not be ideal but I don't think it will impact on pressure. |
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10-03-2017, 07:43 AM
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Quote:
Bad day at the Porsche factory? |
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10-03-2017, 09:07 AM
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My Garage
1971 Porsche 911
Baja Bug
