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Big block oil pressure issues

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Old Jun 29, 2012 | 5:31 PM
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Question Big block oil pressure issues

Hi, Im new to this forum and in need of some help with my corvette. I have a 69 with a 427 in it, I've had it for 32 years, but have not driven it much as I have had this problem since I've owned it. The oil pressure when started is around 40-45 psi, but as the engine temp. Goes up the oil pressure goes down, to zero at temp. 200 deg. range. I have replaced main, rod, cam bearings twice, had the crank cked. At a machine shop for trueness, plastic gauged mains and rods, .001-.0025" tried thicker oil 10-40' 20-50. 2 different oil pressure gauges, 2 different oil pumps with different pick-ups, currently has a mellings m77hv high volume pump, pick up is 3/8 to 1/2 inch from the bottom of the oil pan (7 qt.)
And still has the same issues, has anyone ever encountered this ? Any help would be greatly appreciated. Thanks
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Old Jun 29, 2012 | 5:49 PM
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From: kevinkpk
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Originally Posted by Sonerai2004
Hi, Im new to this forum and in need of some help with my corvette. I have a 69 with a 427 in it, I've had it for 32 years, but have not driven it much as I have had this problem since I've owned it. The oil pressure when started is around 40-45 psi, but as the engine temp. Goes up the oil pressure goes down, to zero at temp. 200 deg. range. I have replaced main, rod, cam bearings twice, had the crank cked. At a machine shop for trueness, plastic gauged mains and rods, .001-.0025" tried thicker oil 10-40' 20-50. 2 different oil pressure gauges, 2 different oil pumps with different pick-ups, currently has a mellings m77hv high volume pump, pick up is 3/8 to 1/2 inch from the bottom of the oil pan (7 qt.)
And still has the same issues, has anyone ever encountered this ? Any help would be greatly appreciated. Thanks
I don't think anything that early had an oil cooler. Does the pressure vary at all at temp with rpm? Those clearances you state are very tight.
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Old Jun 29, 2012 | 7:34 PM
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Default Big block oil pressure issues

Yes, when I raise the engine speed when at temp. the oil pressure will go up, aprox 20 psi @ 2500 rpms
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Old Jun 29, 2012 | 7:54 PM
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I know I read two new guages, if you don't have any "noise" from the engine, place an independant oil pressure guage just to verify.
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Old Jun 30, 2012 | 10:34 AM
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Are you using an electric or mechanical oil pressure gauge?
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Old Jun 30, 2012 | 9:18 PM
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I'm using a mechanical oil guage, and one of the 2 gauges that have been connected was an external guage, still have the same results.
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Old Jun 30, 2012 | 9:25 PM
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So, you are not loosing oil, external or internal?
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Old Jun 30, 2012 | 9:41 PM
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No not loosing oil externally, and I haven't run the engine long enough to see if oil level goes down, but I have no signs of burning oil.
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