Fastdriver1992

iTrader: (1)

long story short, got my car running and i have low oil pressure. surprise surprise. anyways stock rotating assembly with the rods resized for ARP Bolts

Rod Clearances are .0027-.0031

everything i've read so far the LS Engines like .0015-.0022 on the rods.

should i just throw a .001 oversized bearing in there and stop chasing my tail with oil pump/oring issues? or do my clearances seem ok?

20w-50 oil was used

oil pressure 40psi Cold
20psi hot
wont go over 30psi hot on free rev when warm

(40 degrees ambient temperature)

Russ K

iTrader: (1)

The GM production rod bearing clearance is 0.0009 - 0.0025 inch, and the service limit is 0.0009 - 0.003 inch. The production main bearing clearance is 0.0008 - 0.0021 inch, and the service limit is 0.0008 - 0.0025 inch. And this is with the OEM oil.

I would cut your oil filter open to check for bearing material. If ok, sounds like an oil pump/o-ring issue. Was the oil pressure low on the first start?

Did you verify the oil pressure with a test gauge?

Russ Kemp

td1168

iTrader: (2)

I'm running .003" rod bearing clearance and a melling 10296 oil pump. With 5w30 oil my car idles 45 psi at idle when hot and maxes at 70. You've some other issues if your pressure isn't getting up over 30psi when it's hot. As previously mentioned, verify that your oil pressure gauge is reading correctly.

Brief Encounter

iTrader: (6)

I'm curious as to why they resized a cracked cap rod? Clearance between the rod bearing and crank journal is only one piece of the puzzle.
Was the crank polished?
What is bore of the big end of the rod? Are they all the same?
Bearing thickness needs to be verified as well.

If the rods have indeed been resized, then you need to buy bearings with a larger nominal OD, not ID. This could also cause an issue by interfering with bearing crush.

This more than likely isn't where you oil issue is coming from, BUT, you should really find out if they truly did "resize" the rods.

LilJayV10

iTrader: (39)

Oh it sounds like there is going to be some tech going on in here. I like it.

Fastdriver1992

iTrader: (1)

Crank was polished
I gave my machine shop that i trust the rods with rod bolts and told them to check that the rods bore stayed true. They told me everything checked out so wether or not they were resized or how much they were resized i am unsure of. I am sure of the clearances because i measured those myself.
Its a mechanical Autometer Oil pressure gauge that ive been using for 5 years now and never had an issue, worked fine in november 2013
Using a melling 10296 pump(used) but i took it all apart and did not see any signs of wear or damage to it.
I just pulled out the oring last night and everything was fine.
Engine has maybe 10min of run time on it. Like i said i just got it running
My nxt thing is going to be to change the pump to a ported LS6 i have on the shelf. Maybe i missed something when i looked over the used melling pump

Fastdriver1992

iTrader: (1)

Will post a video tonight when i get home

KCS

iTrader: (20)

What are your main bearing clearances? They seem to have a greater influence on oil pressure than the rods since they are upstream of the oil flow path, but the rod bearing clearance is excessive for a stock rotating assembly. If it were me, I would swap the bearings out for .001" under bearings.

Just for reference, I have my mains at .0022" and my rods at .002" and I see 40psi hot idle and 60ish WOT. I'm also using a 10296 pump and 5w30 oil.

Fastdriver1992

iTrader: (1)

To be honest i did not check the mains. I did the stupid thing of "assuming" its a stock rotating assembly so standard bearings and an uncut crank should have no clearance issues. I only checked the rods because i changed the bolts

Gray86hatch

iTrader: (83)

Just pull it and measure everything up. Fix the rod clearance. Running it more is not going to fix it. Pump is not going to fix it.

Why 20-50 proper clearances and the thick oil is not needed

v8pwr

iTrader: (19)

Assumption is your first mistake and not checking everything is your second. While you rod clearance is excessive a 10296 pump should be able to flow enough to keep the pressure up. You may have a problem with the mains or another source that is bleeding off the pressure. Check everything.

RezinTexas

I don't think the rod bearing clearance is your problem. I'm running about 0.003" on my mains (iron block) and rods, and have very high oil pressure (~55 hot idle).

As stated, I think it was a mistake to not measure the main bearing clearance.