Oil guage feed line install question. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

berencam · 04-09-2009, 01:01 PM

Im about to change the line that goes from the engine to oil gauge. Do i need to bleed it and remove the air or will the air not matter. Also what is the reccomended oil pressure for a fresh engine with tight clearances (plastigauged every clearance and they where all in spec but on the tight side), both for idle and for 3-4k rpm. thanks

beautimus · 04-09-2009, 01:35 PM

i wouldn't bleed the oil line, pressure is pressure wheather its oil or air at the end of the line , it doesn't matter.

berencam · 04-09-2009, 01:40 PM

But air compresses, oil doesn't. Seems like it would give a lesser reading.

C20-67_N_MO · 04-09-2009, 04:02 PM

Quote:

Originally Posted by beautimus

i wouldn't bleed the oil line, pressure is pressure wheather its oil or air at the end of the line , it doesn't matter.

x2 Will not matter if air is in the line or not.

berencam · 04-09-2009, 04:23 PM

ok, and the pressure question?

Green Machine · 04-09-2009, 05:34 PM

Even if you bleed it air will get in anyway after you shut it off. Say you have 40 psi oil pressure, the air in the line will be compressed to 40 psi also. If you hooked your gauge to an air tank filled to 40 psi, or an oil tank at 40 psi , it still would read 40 psi. The air does not matter at all.

Jim_PA · 04-09-2009, 07:22 PM

Right. We aren't compressing the oil, just reading the pressure through the line...

68C15 · 04-09-2009, 08:16 PM

as for the pressure expected; this an impossible question. granted your bottom end may be good and tight but the important part is the cam bearings. this is where oil pressure is lost or retained.
a general rule of thumb is 10 psi per 1000 rpm. most oil pressure light switches turn on at 7psi.

berencam · 04-09-2009, 10:01 PM

Well im over about double that, at idle(cold) im at 50 4k rpm cold im at 85. Now when the truck has warmed up it will drop to 40ish idle and 70 at 4k rpm. Is this safe operating range?

Green Machine · 04-09-2009, 10:35 PM

SBC ? If you used a high volume pump with a high pressure spring, that sounds about right. What is the intended usage ? Personally I like to use a high volume pump with a standard pressure spring, holds great oil pressure at idle without getting too crazy going down the road.

**clay68c10** · 04-09-2009, 10:56 PM

That sounds like ok pressure to me, maybe a little high from the tight tolerances.
My BBC holds over 40psi at 2500rpm when hot (rebuild 10k miles ago) and around 20psi at idle.

berencam · 04-09-2009, 11:11 PM

sbc yes, standard pump also. I also need to change the oil i still have assembly lube in it that i just remembered about. (the engine has less than 2 hours run time on it) That is what could/ probably causing the high reading.

68C15 · 04-10-2009, 05:13 AM

you're good to go for pressure. I don't like to have too much volume as it tends to put a bunch of oil up top and leave the pan about empty.

04-09-2009, 01:01 PM	#1
berencam Registered User Join Date: Aug 2007 Location: branson mo Posts: 933	Oil guage feed line install question. Im about to change the line that goes from the engine to oil gauge. Do i need to bleed it and remove the air or will the air not matter. Also what is the reccomended oil pressure for a fresh engine with tight clearances (plastigauged every clearance and they where all in spec but on the tight side), both for idle and for 3-4k rpm. thanks __________________ 69 chevy c10 350 3 speed manual wood bed build thread here r.i.p. 70 c10 auto 350 build here

04-09-2009, 01:35 PM	#2
beautimus Registered User Join Date: Mar 2002 Location: woodstock, alabama, usa Posts: 938	Re: Oil guage feed line install question. i wouldn't bleed the oil line, pressure is pressure wheather its oil or air at the end of the line , it doesn't matter. __________________ i survived cancer and kidney stones, but my kids are killing me.

04-09-2009, 01:40 PM	#3
berencam Registered User Join Date: Aug 2007 Location: branson mo Posts: 933	Re: Oil guage feed line install question. But air compresses, oil doesn't. Seems like it would give a lesser reading. __________________ 69 chevy c10 350 3 speed manual wood bed build thread here r.i.p. 70 c10 auto 350 build here

04-09-2009, 04:23 PM	#5
berencam Registered User Join Date: Aug 2007 Location: branson mo Posts: 933	Re: Oil guage feed line install question. ok, and the pressure question? __________________ 69 chevy c10 350 3 speed manual wood bed build thread here r.i.p. 70 c10 auto 350 build here

04-09-2009, 05:34 PM	#6
Green Machine Senior Member Join Date: Jul 2004 Location: Estherville, Iowa Posts: 3,371	Re: Oil guage feed line install question. Even if you bleed it air will get in anyway after you shut it off. Say you have 40 psi oil pressure, the air in the line will be compressed to 40 psi also. If you hooked your gauge to an air tank filled to 40 psi, or an oil tank at 40 psi , it still would read 40 psi. The air does not matter at all. __________________ 1968 C10 307 3spd Long Fleet ------ http://67-72chevytrucks.com/vboard/s...d.php?t=201103 1970 C10 305 Super T10 Long Fleet --- http://67-72chevytrucks.com/vboard/s...d.php?t=202285 1971 C20 383 TH350 Dana Posi ----- http://67-72chevytrucks.com/vboard/s...d.php?t=206894 2001 GMC Sierra 1500 C3 6.0

04-09-2009, 07:22 PM	#7
Jim_PA Registered User Join Date: May 2005 Location: PA Posts: 2,696	Re: Oil guage feed line install question. Right. We aren't compressing the oil, just reading the pressure through the line...

04-09-2009, 08:16 PM	#8
68C15 blood type; Retumbo Join Date: Jan 2004 Location: next to my reloading bench Posts: 10,269	Re: Oil guage feed line install question. as for the pressure expected; this an impossible question. granted your bottom end may be good and tight but the important part is the cam bearings. this is where oil pressure is lost or retained. a general rule of thumb is 10 psi per 1000 rpm. most oil pressure light switches turn on at 7psi.

04-09-2009, 10:01 PM	#9
berencam Registered User Join Date: Aug 2007 Location: branson mo Posts: 933	Re: Oil guage feed line install question. Well im over about double that, at idle(cold) im at 50 4k rpm cold im at 85. Now when the truck has warmed up it will drop to 40ish idle and 70 at 4k rpm. Is this safe operating range? __________________ 69 chevy c10 350 3 speed manual wood bed build thread here r.i.p. 70 c10 auto 350 build here

04-09-2009, 10:35 PM	#10
Green Machine Senior Member Join Date: Jul 2004 Location: Estherville, Iowa Posts: 3,371	Re: Oil guage feed line install question. SBC ? If you used a high volume pump with a high pressure spring, that sounds about right. What is the intended usage ? Personally I like to use a high volume pump with a standard pressure spring, holds great oil pressure at idle without getting too crazy going down the road. __________________ 1968 C10 307 3spd Long Fleet ------ http://67-72chevytrucks.com/vboard/s...d.php?t=201103 1970 C10 305 Super T10 Long Fleet --- http://67-72chevytrucks.com/vboard/s...d.php?t=202285 1971 C20 383 TH350 Dana Posi ----- http://67-72chevytrucks.com/vboard/s...d.php?t=206894 2001 GMC Sierra 1500 C3 6.0

04-09-2009, 10:56 PM	#11
clay68c10 Senior Member Join Date: Aug 2004 Location: Centennial, CO Posts: 2,995	Re: Oil guage feed line install question. That sounds like ok pressure to me, maybe a little high from the tight tolerances. My BBC holds over 40psi at 2500rpm when hot (rebuild 10k miles ago) and around 20psi at idle. __________________ ClusterTruck: 68 C10 Bought in 89, wrecked in 03. Slow low $ rebuild started '17. 6.0 & TKO http://67-72chevytrucks.com/vboard/s...d.php?t=788602 93 K1500 Short Step, 350, NV4500, EBL flash ECU. Vortec heads & roller cam someday... 05 Jeep Wrangler Unlimited. 3” lift & 6-speed 02 E320 the insurance total “free car” 13 Tahoe LTZ Last edited by clay68c10; 04-09-2009 at 10:57 PM.

04-09-2009, 11:11 PM	#12
berencam Registered User Join Date: Aug 2007 Location: branson mo Posts: 933	Re: Oil guage feed line install question. sbc yes, standard pump also. I also need to change the oil i still have assembly lube in it that i just remembered about. (the engine has less than 2 hours run time on it) That is what could/ probably causing the high reading. __________________ 69 chevy c10 350 3 speed manual wood bed build thread here r.i.p. 70 c10 auto 350 build here

04-10-2009, 05:13 AM	#13
68C15 blood type; Retumbo Join Date: Jan 2004 Location: next to my reloading bench Posts: 10,269	Re: Oil guage feed line install question. you're good to go for pressure. I don't like to have too much volume as it tends to put a bunch of oil up top and leave the pan about empty.



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