Surprizing wear for over 300k miles
 

When I removed the rod bearings I saw something that really gave me a shock. They looked like about 100k miles or less. I was expecting to see more copper. Same with the mains. There's one rod bearing missing, I think I may have chunked it, but it's the same as the others.

the big question is- what oil? I assume this was a completely stock engine too? what filter?

Was there an issue that caused you to tear it down or did you just think it was time for a fresh start?

K

I would bet its been rebuilt in its life time. How are the bores do they measure stock? Been to the dealer for major engine trouble they may have replaced them without telling you all the details.

doesn't matter, if it wasn't rebuilt in it's life time, it's because of
efi.. and it's cold starts..

Completely stock engine,
Castrol GTX 20-50 since I've owned it, (got it with about 97k on it) Switched to Castrol High mileage at about 180k.
AC Delco filter. Allways.

Never had an overhaul that I know of. If it did, it would have been done 253,000 miles ago, I got it with 97k on it, from the guy that bought it new, many years ago.
Bores are fine, with negligable wear, You can almost catch your fingernail on the ridge. I ran a hone through the bores, and ridge was gone, musta been just carbon.

Yes there was an issue. It developed a solid miss, and losing coolant.
So I figured a head gasket. And with that many miles there's no way I'd do the heads, and not the rest. If it wasn't such a nice car, I'd not even fool with it. Thought about getting a new engine from GM, but when I got the heads off, I decided to save the money for something else.

I'm totally amazed at this engine. and how it's held up.

If a Quadrajet Carburettor = efi, then mabe so.

I used to use gtx 20-50 since it was so thick it really does keep things lubed its slow to roll down the cylinder walls. Clearly good for bearings as well. I may need to switch back since i notice most new oil smells pre burnt these days. Works great in really hot running engines.

Things get changed and the customer never knows sometimes. Just got a bill larger than normal. I seen a turbo put on a brand new car and wasted the motor cause the rings and plated bore was not up to the job and it failed. Engine was rebuilt and the customer picked it up. We tried to explain but he just said you got it worked put right? So i am sure that guy had no clue what was done to his motor. Sometimes mechanic make mistakes and just fix them and think its ok not to say anything since they fixed it. You can usally identify oem parts over replacement check the back and see what the name is on them gm marks everythng twice at least. They are un read able usally but they are marked. After market bearing always have a size on the back next to the name.

nope,, but most don't keep the q-jet in tune so . the choke washes the walls at start up..
the oil didn't get that much better..
and why efi engines can go 7-10k on oil and carbs go 3-3500..
cold starts..

That only works when All the parts of the EFI system are working properly.
A bad temp sensor can wash down the cylinder walls, an' fill the oil pan with gas, faster that you can say scat.

Newer cars dont need as many oil changes since most are synthetic oil. Now with normal oil they call for 3000 miles just as carb car did.

Running a car pig rich does have some effect on oil but normal tune vs efi not much different. Usally about care and abuse.

This is all factory stuff. So anything done, would have been done prior to 97k miles, at the dealer. I perform all my own maintenance. Back in the late 70's/early 80's, I started using Castrol, because it was reccomended by the only manufacturer (at that time) to give a standard 100k mile warrenty. So I figure that while the big 3 were offering 60k, and the other was offering 100k and reccomending Castrol, I'd run it too.

Thats pretty good. I take it you dont rev it and follow a normal start up proceedure every time and probably touch the gas before you turn back the key to shut it off? I know a few older mechanics that swear by the start up and let it turn for at least a few seconds before you slam it into gear. And they always said touching the gas before you shut it down makes it fire right off and make it fire quicker next time. Also keeps the carbon from sticking to the back of the valves. Its always the cold starts that take out the bearings.

I treat my cars like crap. Comes from living in the city nothing last might as well run it. I may change back to gtx 20-50 i got used to thinking it was worth the hp and fuel savings to run the lighter oils but i noticed if you overheat the engine or really beat on it with the thin oils it does not survive as well. You can never go wrong with delco either.

One things for sure it was not built on a friday!