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Discussion Starter · #1 ·
Ok guys i have a 67 327 4 speed that pulls strong but when it first fires up it has 40 lbs pressure, than once warm drops down to like 25-30 but at a red light drops to like 5lbs?

it has 30 weight engine oil now, what's a thicker oil i can run to help boost oil psi without replacing the oil pump?
 

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1968 Camaro LS3 TH400 Moser 9” DSE mini tubs
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IMHO
You should verify that pressure on a reliable gauge, then decided to rebuild or let it take its self apart.
Your pressure is a result of bearing clearances that are showing wear. ( well….a subjective guess from this side of a keypad anyway)
It would be a shame to let it grenade.
 

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Has anything changed recently (new issue) or this came in slowly ?

Been hearing about some oil filters having bypass issues, and if this is "new", it could be something that simple.

BUT, I do agree... start looking into rebuilding or a replacement.
 

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How long have you had the car and if a while is it a trend that the oil pressure is dropping?

I would start by using a multi viscosity oil at your next change and get an oil analysis. The oil analysis will tell you if you have bearing problems most likely. I'd be surprised if your oil pump is causing low pressure.
 

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68 SS/RS, 468 BB 4 speed, 3.73 Posi, new paint, motor mods , trans and diff assembly. 2" Drop
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I think a lot of people get overly concerned when hot idle pressure get down to 5-10 especially on a 50 yo gauge. My BBC runs 45-50 hot and appears to be 10 at idle on stock gauge, Im using 10-30 Driven oil. In process of switching to 10-40, well see if that changes.
 

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1968 Camaro LS3 TH400 Moser 9” DSE mini tubs
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I think a lot of people get overly concerned when hot idle pressure get down to 5-10 especially on a 50 yo gauge. My BBC runs 45-50 hot and appears to be 10 at idle on stock gauge, Im using 10-30 Driven oil. In process of switching to 10-40, well see if that changes.
I was ok when the valves barely wiggle, instead of lifting. Pulled them all and they were dished but not flared. Oil pressure was still 28 psig.
I’m not personally ok with 5-10 at idle on a SBC,
I have seen the result of allowing that to go on for prolonged periods on the BBC work truck we drove, a 1978? 2+2 454 TH400 , you know the one it takes two lanes to make a 180 turn.
Maybe an isolated incident, but not worth testing it.
 

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'68 396 SS/RS, '97 SS, '02 SS
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Likely the oil pump is nearing the end of its serviceable life. I had a SB in a K5 Blazer that did this same thing and until I could get the time to drop the pan and replace the pump. I added Lucas Oil Stabilizer to the oil and it increased it by maybe 3-5 psig.
 

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Discussion Starter · #13 ·
im going to replace the pump this fall and try to make the engine last 2 -3 years before pulling it for a skip white 383, the engine 327 in it pulls hard now just dont like oil psi dropping to 10lbs at a red light then 30-40 on highway... they want like 1500.00 labor ill do alittle each night till i get pan off, its not THAT HARD... just a pain..
 

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OP....I would not spend the $ on replacing a oil pump you don't know is "bad" (read they RARELY fail)

Run 20-50 and see if your oil pressure is higher, it should be. This will buy you time, likely years. With this said bearing wear is the common issue with low oil pressure.

"Generally," a SBC wants 10 psi for every 1k rpm...so a motor idling at 700 rpm ..7 psi is fine if oil pressure otherwise increases to 25-40 under normal full engine temp use
 

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I would switch to a 10w 40 and stop worrying about it. The engine is probably just worn out and changing the oil pump is not going to fix the real problem. My S-10 just turned over 300k miles and it basically has had almost no oil pressure hot when idling and about 30 going down the road. Its been that way for the last 100K miles or so :)

I would put a mechanical gauge on it just to be sure like others have said.
 

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68 SS/RS, 468 BB 4 speed, 3.73 Posi, new paint, motor mods , trans and diff assembly. 2" Drop
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I agree with what Bill said too. I was just going post if you have 10 at idle and 40 going down the road, all is good. At idle there is no load on the motor, as I look at it as long as you have adequate positive pressure rock on!
 

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40 cold and 25 hot is normal stock oil pressure. First thing I would do is install a mechanical oil pressure gauge if there isn't one already. next change filter only and see if any difference. Any pressure at idle should be sufficient to maintain oil film between bearings. Again, mechanical oil pressure gauge and braided stainless line with threaded fittings at each end would be best money spent in my opinion,

Shorty after I switched to synthetic oil, I fired up the car early to head to work and was greated with a mechanical oil pressure gauge that was showing me 10psi cold. lower than 5 at idle. Slightly in panic about my engine and letting the fella I work with down I headed to work with my eyes glued to the pressure gauge. Made it there and back with no knocks developing. Turned out to be a clogged oil filter.
That happened two more times till the synthetic oil cleaned out the engine.

The reason my pressure gauge showed me what was actually going on is I have the factory bypass filter adapter replaced with a non bypass unit. Had I not replaced that I would never have known the filter was clogging and never known how much the syntetic oil cleans out the old oil sludge.
 

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68 SS/RS, 468 BB 4 speed, 3.73 Posi, new paint, motor mods , trans and diff assembly. 2" Drop
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Also keep in mind the oil feed line is a dead end leg of a circuit and if theres air in the line it may take some time to get a correct reading.
 
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