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I have a 1973 chevy 350 with about 30k miles on it. It is pretty stock except for some mild heads, intake, rv cam, and carb. When the engine was new, cold start oil pressure was 65 psi. When warm sitting in gear it would show 14psi. Now, after 30k miles, on a cold start oil pressure still shows 60-65 psi. When warm and sitting in gear it shows 10 psi. I have been noticing it slowly dropping. A month ago it was at 12 psi and now it is at 10 psi. At 60 mph it used to show 50psi and now it shows 47psi. What do you think is going on? I changed the oil, no difference. Oil is clean. I use 10w30 all the time. Is my oil pump going out or am I starting to get excessive clearance problems? Any help is appreciated. Also, I hooked up a different gauge and got the same results. So I know the gauge is not the problem. Thanks!
 

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Normally, you would see a slight drop in pressure as the engine gets a little older and the rings and bearings wear in. I don't see where your current pressures are a problem.
 

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I know my pressures are not bad yet, but I just continue to see a drop in pressure every couple months. 14-12-11-10 psi. Just don't know if there is a problem occuring. I don't think pressure should be dropping that much should it?
 

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when you changed the oil did save the oil filter ? you could carfuly cut it open and dicect the inerds for a clue as to what mite be going on. a big magnifing glass could shed some lite.
 

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well if it's dropping that fast then your "new" oil filter should still be able to tell you something about it, if not, then it will soon.

i agree with you... a psi every month or two would worry me also.
 

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did the hidden plug at the rear main get re placed if it was not put back in it will cause a oil leak inside the motor it also sounds like a bearing clearance problem to me was the crank reground new right berings was motor oil primed before starting? it really sounds to me like u oughta check your bearings u may find a surprise waiting let me know if the bearings wore down to copper! was the cam bearings replaced ? do you hear any rataling if so its the mains was the engine balanced it makes the bearings last longer but i would check the bearings they will tell whats going on!!!!!!!!!!!
 
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