92_Corvette

iTrader: (1)

I just rebuilt an lm7 that had no oil pressure. Hot tanked it, honed, bearings, pistons, rings, lifters, mild cam, valve springs, new oil pump and dumbbell in back of block.

on a cold idle oil pressure is about 30, and hot idle is 20-25.
Cruising at 1800 rpm its 30 psi when hot.

Do these pressures look ok for a fresh rebuild with 5w30? I've seen some of the 5.3 in stock silverados have 40 at idle.
The motor I took out was a fairly fresh 355 with 10w40 it pegged 60 psi on a cold start and would be around 35 at a hot idle.

And the coolant temp is got me spinning circles as well. My gauge shows about 160 when fully warm, I put the sending unit at the back of the passenger head. With a temp gun the water pump, heater core feed hose, and the front of the drivers head are all about 180-190. My temp gauge was accurate with the old motor, I tried using the old sender with an adapter and it read 160 but it was to far from the head and when I was to drive the car the gauge would go to full cold. So I thought that was the problem and went with a temp sender from a 98 trans am. Now this sender is in the head as should be and doesn't cool down when driving but still never reads higher than 160. So is the back side of the head actually that much cooler than the front of the head? Do I need to move the temp sensor?

gagliano7

On my 5.3 cold oil pressure at idle is 50 and hot idle a hair under 40. Cruising i am around 55 psi. Yours seems on the low side. How far does it go up at WOT? Maybe on the rebuild the clearances are bigger.

92_Corvette

iTrader: (1)

I plastigauged the rods and mains and they were bigger than .002 but les than .003

92_Corvette

iTrader: (1)

At 4000 rpm its 40 or 45. I'm gonna double check with a mechanical gauge this weekend

gagliano7

You are within spec but a little lower than most. Maybe with you bigger clearances you need to run a thicker oil.

92_Corvette

iTrader: (1)

I think my sending unit was the problem. I checked it with a mechanical gauge when I changed the oil. It was 30 at a hot idle. Reinstalled the sending unit it and the gauge is reading 30 as well, still a little lower than I've seen in stock applications, but I feel a lot more comfortable there.

Now for this coolant temp reading? I'm thinking maybe it is the sending unit as well?

CAMSTER

iTrader: (10)

Do you have a double timing chain? If so the spacer in the drivers side may be installed upside down causing a 40% blockage of the oil transfered from pump to engine block.

Now water temps cooler in the rear may be cause by an air pocket in the back of the heads common when not using steam pipes in the rear.

Hope this helps.