turnpike_cruiser

I’ve noticed that when pushing my 455 over 4,000 rpm (I don’t do this often). The engine has a sound nasty, not a ‘good’ nasty sound, and the oil pressure drop to less that 5 psi. As soon as I let off, the pressure comes back to 45/50 psi. With the engine warm, the idle pressure is 10/15 psi. From what I remember the oil pump is stock as a rock.

This engine has about 75,000 miles on it since the last rebuild (a mediocre one at that back in 1976), the crank is 10 under on the rods (it came from the factory that way) and stock on the mains. It still runs strong, but I have visions of the bottom end going south soon.

I am wondering if this is the classic ‘Olds too much oil to the top end problem’ finally showing up. I’m getting ready to rebuild another 455. This will just be a street engine, no formal strip time. I plan on building the motor to handle the occasional 5,500 to 6,000 rpms. So is it necessary to run oil restrictors on a street engine? Just what is the general consensus about oil restrictors anyway?

TIA

Oldsguy

You are probably partially right, but 75,000 miles on a rebuild is quite a bit, and even at 4,000 rpm for a 455 that is medium to high rpms. I think there are lots of 455s out there that lose pressure that way. You will probably get arguments both for and against the restrictors. We have a few threads on that subject already, some say do it, some say don't need to.

Run to Rund

bigger pan, more oil capacity!

citcapp

X2 on the bigger oil pan

MN71W30

I'm starting to believe that Oldsmobiles may have more of a windage problem because of the long stroke than a need for restrictors. I just posted a thread about the same problem I had after running my motor down the highway for 20+ miles at 3k rpm. My pressure began to drop. After I pushed in the clutch and coasted for 10 seconds it returned to 55 psi from a lowest reading of 48 psi. I would consider running a deeper pan and experement with oil levels. My BBC 496 had the same trouble and had less of a pressure drop with the pan being 1 quart low.
Let us know what youy find.

J-(Chicago)

The 2 olds oiling issues that I personally believe to be negative, are the multi angle drainbacks in the heads, and the crank journal size.

If the drainbacks in the heads are clogged, there is your problem. Sludge will kill the engine. There are no big rectangular cutouts in the heads like a small block chebby. A Chebby can have clogged lower drainbacks, and the uppers will still function once the valve cover starts filling up. Olds only has the lowers.

Also the big diameter crank journal takes more effort for the oil to creep around the whole thing from 1 oiling hole.

J-(Chicago)

Cleanliness is godliness as far as engines go. Maintenence is key.
You could have a 20 quart pan, and it wouldn't do a damn thing for you if the engine is filthy.

turnpike_cruiser

Not the problem here. Engine is clean, no sludge build up on the heads.

turnpike_cruiser

Not the problem here. Just changed about 200 miles ago. Oil on dipstick still looks fresh.

Really this is a clean engine, oil gets changed 2 or 3 times a year, regardless of mileage.

I checked the oil level a few days ago. Might be 1/2 qt low. Regardless of oil changes it's been making this noise for a few years. Pretty much the norm for this engine, that's not to say everything is right either.

J-(Chicago)

The engine certainly looks great in the pictures.
The only other things that come to mind are a carboned up valley, or the oil pump pickup not having correct clearance from the bottom of the pan.
If your heat crossover isn't sealed up tight, it will blow heat into the valley and carbon everything up, thus slowing drainback to the pan.
Pump pickup to bottom of pan gap should be about 10mm

turnpike_cruiser

I changed the intake manifold a few years ago. The old Offy had developed a crack in the heat crossover on the bottom of the intake. The valley pan gasket did have some carbon buildup on the top, but the valley was free of carbon buildup and sludge.

Can't say what the clearance between the oil pump and pan is. My Dad and I did the rebuild over 34 years ago and to check something like that never crossed my mind.

My Dad was a mechanic at an Olds dealer in South Gate California at that time. He was old school and not one for checking clearances, just how things 'felt' to him. But on this rebuild that came back to bite him. We basically just put in rod and main bearings, honed the cylinders, installed new rings, a 68 Hurst/Olds cam and did a ho-hum valve job.

We got everything back together, got the motor back in the car and cranked it up. ALL 8 rods where knocking! Was my Dad ever upset. He went digging through the trash for the old rod bearings and discovered the bearings where 10 under from the factory! The engine was out of a totaled 68 Delta wagon with about 60k on the engine. You could tell the engine had never been opened up before we pulled it out. He never check the bearings and put standard bearing back in. Yup had to pull the engine and install 10 under bearings.

Even though not much was checked when putting things back together, this engine has been pretty strong and at times in my younger days I really put it through hell.

I've learned a lot over the years. This time around this new engine is going to be measured and checked more than any engine I've rebuilt before.