Another BBC oil pressure question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ZEKE68 · 09-08-2018, 10:05 PM

Got my big block running and been having some issues with the oil pressure gauge. I am running an Autometer electric, and I am losing trust in the gauge, Put a second sending unit in, and then the gauge seemed like it was sticking at first. Anyway now it is showing around 20 psi at idle, and about 35 psi at 3000 rpm. Went to 4000 and it didn't go any higher. This is with Valvoline 10W30 oil. Does this seem like a safe amount of oil pressure? I may get a mechanical oil pressure gauge after all of this.

**Steeveedee** · 09-08-2018, 10:51 PM

How many miles on it? Mine was rebuilt a couple of decades ago (~100k miles on it since then), and pegs the gauge when cold. I don't like that, but it's been that way since the rebuild. It now runs about 30 PSI at hot idle, if the gauge max is 80 PSI. If the gauge max is 60 PSI, then the hot idle is about 25 PSI. 20 PSI isn't that bad, I would think. I run 10-40, though. Truth is, the lighter the oil you run, as long as there is a film present, you should be good to go.

mike16 · 09-08-2018, 11:48 PM

cold pressure or hot.

20 at the low end is a bit low but with 30 wt warmed up it might be normal for an older engine.

the high pressure at higher rpm is a bit more concerning.

change to a 40 wt and see what happens when its warmed up.

next fix would be to put a high volume hi pressure pump in there and see what that does to psi hot at high rpm but watch that cold pressure on start up.

may be just tired old truck engine

Redneck Rydes · 09-09-2018, 07:19 AM

I would try a mechanical gauge just to be sure.

ZEKE68 · 09-09-2018, 09:19 AM

Newly rebuilt motor. Hot. I am going to change the oil filter to make sure it is not plugging up with assembly lube first. Then I will try 40W. Already ordered a mechanical gauge.

Redneck Rydes · 09-09-2018, 09:57 AM

Be careful of the 40 weight,don't rev when cold,you could blow out the rear seal,other problem would be oil not travelling fast enough on start up and starving rods and cam bearings, 10 w 40 would be better,

RustyBucket · 09-09-2018, 02:05 PM

O'rielly has a $14 mechanical gauge... shows in stock. I'd hafta know TODAY.

I have 25-30k miles on a .40 over 454 in the Blazer. I run 20/50 and the mechanical gauge shows a tad over 60lb at 2000 rpm cold and a little over 40lb at a 700 rpm idle. It looses about 10lb over all when it warms up. Not sure if my gauge is dead accurate but it's consistent.

ZEKE68 · 09-09-2018, 02:34 PM

Took off the break in Wix and put on a K&N filter, and now I have 30 psi at idle and about 45 psi at 3500 rpm. Feel a lot better. Not completely warmed up.

RustyBucket · 09-09-2018, 03:09 PM

GOOD NEWS!!! Did you cut the break-in filter open to see what it had caught?

ZEKE68 · 09-09-2018, 03:47 PM

Don't have a cutter to open it up. If I hack saw it open I don't think I would be able to tell much.

**clay68c10** · 09-10-2018, 08:52 AM

You can cut it with a big set of wire cutters on the flange. That doesn't make too much of a mess.

mike16 · 09-13-2018, 07:22 AM

Quote:

Originally Posted by zeke68

took off the break in wix and put on a k&n filter, and now i have 30 psi at idle and about 45 psi at 3500 rpm. Feel a lot better. Not completely warmed up.

yes that is good news

09-08-2018, 10:05 PM	#1
ZEKE68 Registered User Join Date: Jul 2012 Location: Space Coast, Florida Posts: 403	Another BBC oil pressure question Got my big block running and been having some issues with the oil pressure gauge. I am running an Autometer electric, and I am losing trust in the gauge, Put a second sending unit in, and then the gauge seemed like it was sticking at first. Anyway now it is showing around 20 psi at idle, and about 35 psi at 3000 rpm. Went to 4000 and it didn't go any higher. This is with Valvoline 10W30 oil. Does this seem like a safe amount of oil pressure? I may get a mechanical oil pressure gauge after all of this. __________________ 1968 SWB Step Side, Big Block, 4L80E , Running!

09-08-2018, 10:51 PM	#2
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,275	Re: Another BBC oil pressure question How many miles on it? Mine was rebuilt a couple of decades ago (~100k miles on it since then), and pegs the gauge when cold. I don't like that, but it's been that way since the rebuild. It now runs about 30 PSI at hot idle, if the gauge max is 80 PSI. If the gauge max is 60 PSI, then the hot idle is about 25 PSI. 20 PSI isn't that bad, I would think. I run 10-40, though. Truth is, the lighter the oil you run, as long as there is a film present, you should be good to go. __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA

09-08-2018, 11:48 PM	#3
mike16 Registered User Join Date: Dec 2009 Location: bisbee, arizona Posts: 1,529	Re: Another BBC oil pressure question cold pressure or hot. 20 at the low end is a bit low but with 30 wt warmed up it might be normal for an older engine. the high pressure at higher rpm is a bit more concerning. change to a 40 wt and see what happens when its warmed up. next fix would be to put a high volume hi pressure pump in there and see what that does to psi hot at high rpm but watch that cold pressure on start up. may be just tired old truck engine

09-09-2018, 07:19 AM	#4
Redneck Rydes Registered User Join Date: Feb 2016 Location: Trenton,Ontario & South Carolina Posts: 755	Re: Another BBC oil pressure question I would try a mechanical gauge just to be sure.

09-09-2018, 09:19 AM	#5
ZEKE68 Registered User Join Date: Jul 2012 Location: Space Coast, Florida Posts: 403	Re: Another BBC oil pressure question Newly rebuilt motor. Hot. I am going to change the oil filter to make sure it is not plugging up with assembly lube first. Then I will try 40W. Already ordered a mechanical gauge. __________________ 1968 SWB Step Side, Big Block, 4L80E , Running!

09-09-2018, 09:57 AM	#6
Redneck Rydes Registered User Join Date: Feb 2016 Location: Trenton,Ontario & South Carolina Posts: 755	Re: Another BBC oil pressure question Be careful of the 40 weight,don't rev when cold,you could blow out the rear seal,other problem would be oil not travelling fast enough on start up and starving rods and cam bearings, 10 w 40 would be better,

09-09-2018, 02:05 PM	#7
RustyBucket Registered User Join Date: Jul 2009 Location: Space Coast, Fl. Posts: 1,050	Re: Another BBC oil pressure question O'rielly has a $14 mechanical gauge... shows in stock. I'd hafta know TODAY. I have 25-30k miles on a .40 over 454 in the Blazer. I run 20/50 and the mechanical gauge shows a tad over 60lb at 2000 rpm cold and a little over 40lb at a 700 rpm idle. It looses about 10lb over all when it warms up. Not sure if my gauge is dead accurate but it's consistent. __________________ Dad always said, "Son, WISH IN ONE HAND, and ......." -------------------------------------- -------------------------------------- Current toy trucks: '71 GMC 1500 SUPER CUSTOM short/step, orig. dk. blue, 350/700r, ps,pb, A/C '72 Blazer 2wd, ochre & white, 454, tremecTKO 500 5spd. ps, pb, A/C, tilt Last 10yrs of hobby vehicles, had a FEW more in the 50yrs. before these: '66 Plymouth Belvedere City of Miami cop car clone. '70 Nova 406"sb, 13.5-1, solid roller, Brodix, p.glide/t.brake, back halved, 9" Ford, spool 4.88, cage,ladder bar/coilover, 10.5 tire....... SOLD!! '67 C10 short/step side mount spare -- SOLD!! '72 Jimmy 2wd, 350/350, ps, pb, fun driver, lots of bondo & a shiny red paint job..... SOLD!! '69 Nova 350, 4spd, A/C, ps, p.b, ...SOLD!!

09-09-2018, 02:34 PM	#8
ZEKE68 Registered User Join Date: Jul 2012 Location: Space Coast, Florida Posts: 403	Re: Another BBC oil pressure question Took off the break in Wix and put on a K&N filter, and now I have 30 psi at idle and about 45 psi at 3500 rpm. Feel a lot better. Not completely warmed up. __________________ 1968 SWB Step Side, Big Block, 4L80E , Running!

09-09-2018, 03:09 PM	#9
RustyBucket Registered User Join Date: Jul 2009 Location: Space Coast, Fl. Posts: 1,050	Re: Another BBC oil pressure question GOOD NEWS!!! Did you cut the break-in filter open to see what it had caught? __________________ Dad always said, "Son, WISH IN ONE HAND, and ......." -------------------------------------- -------------------------------------- Current toy trucks: '71 GMC 1500 SUPER CUSTOM short/step, orig. dk. blue, 350/700r, ps,pb, A/C '72 Blazer 2wd, ochre & white, 454, tremecTKO 500 5spd. ps, pb, A/C, tilt Last 10yrs of hobby vehicles, had a FEW more in the 50yrs. before these: '66 Plymouth Belvedere City of Miami cop car clone. '70 Nova 406"sb, 13.5-1, solid roller, Brodix, p.glide/t.brake, back halved, 9" Ford, spool 4.88, cage,ladder bar/coilover, 10.5 tire....... SOLD!! '67 C10 short/step side mount spare -- SOLD!! '72 Jimmy 2wd, 350/350, ps, pb, fun driver, lots of bondo & a shiny red paint job..... SOLD!! '69 Nova 350, 4spd, A/C, ps, p.b, ...SOLD!! Last edited by RustyBucket; 09-09-2018 at 03:33 PM.

09-09-2018, 03:47 PM	#10
ZEKE68 Registered User Join Date: Jul 2012 Location: Space Coast, Florida Posts: 403	Re: Another BBC oil pressure question Don't have a cutter to open it up. If I hack saw it open I don't think I would be able to tell much. __________________ 1968 SWB Step Side, Big Block, 4L80E , Running!

09-10-2018, 08:52 AM	#11
clay68c10 Senior Member Join Date: Aug 2004 Location: Centennial, CO Posts: 2,932	Re: Another BBC oil pressure question You can cut it with a big set of wire cutters on the flange. That doesn't make too much of a mess. __________________ 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



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