I pulled the heads last night and found this one cylinder cleaner than all the others. sorry I didn't think to taking a picture of the head but the exhaust valve has a brown carbon covering but does not appear to be burnt. I am taking the heads down to be checked. This motor is a remain about 10,000 miles ago.
My first thought was water, but the gasket has no signs of leakage. Now the plug looks like it is newer/not firing all the time. But the last time the motor ran was nice and smooth. So what could this be from?

 

Looks to me like water is entering that cylinder somewhere.

Shame we can't see the combustion chambers.

- Eric

 

Stupid me forgot I had them still out in the trunk. Anyway will these help. Water was My first thought as well but from where?

 

It looks like it was coming in from between #4 and 6 cylinders by this pic:

 

Well I just got back from the machine shop and I'm in for a full valve job OUCH! So much for buy a car with a remanufactured motor. I know I know they only do the minimum they have to. So my next move is to see if for chance, slim as it may, find out if the cylinders were bore. If not they recommend doing the bore and put new pistons in. If I have to do this I am going to need you help for a good piston to go with #8 heads. I am not wanting massive HP but some to have some fun if the hair raises its self.

 

Yep your right I see it now. Thanks! A good Felpro will fix that!

 

Based on this picture, I'm not so sure it's water.



I wonder whether that one is running lean and overheating the exhaust valve.

- Eric

 

Any compression check done before removal? How much ridge in cylinders? I would not start talking pistons and bore before measuring bore, and would do that before removing pistons. Would also make sure machine shop knows about Olds heads before treating it like a Chevy.

 

Compression was 140 to 145 stone cold. No ridge, block was bored .040 over this is a remain motor. Machine shop is one of the best in our area. Yes knows the difference for olds 350. From what my machinest says that if it was bored the bottom end should be good. I can still see the cross hatch. From what I found out tonight I am going to leave the bottom end alone.

 

How does one cylinder runlean ? not doubting just trying to understand?

 

Vacuum leak, typically from intake<->head surface or a vacuum fitting in that runner

 

I want to thank everyone for there input. If I would have looked closer I would have found the smoking gun. Crappy head gaskets can cause a multitude of problems. I only use Felpro gaskets and have never had a problem.
Finding that the block was bored and new pistons I feel better about the bottom end. However I will be checking all the main and rod bearings. With it in the engine stand this is a no brainer.
You would not believe how bad the heads where done. I was right there when my machinist popped the valves out. No harden seats for the exhaust, bronze sleeved guilds, cheap seals, and the shafts of the valves where scraped and had a lot of play in the guilds. My thoughts are only the bottom end was remained.
Anyway I won't see my heads for 7 to 8 weeks, this shop is one of the best and cannot keep up with the demand. They do it one way RIGHT! and in no hurry to do it just to get it out the door. They are about $200 more for both heads but they will be better than new and will be able to handle this crappy gas we have to burn. They know that Olds is spelled differently than Chevy.
Funny how these restorations morph into "AHHH NOW WHAT?"

 

Sleeved guides need more play - about .004". They feel loose.
That white exhaust valve probably wasn't sealing, so it got cherry red and looks cleaner than the rest. That cylinder doesn't look lean, the valve just looks cooked, and terribly recessed.

I'd shop out the price on aftermarket heads considering what it costs to get a set rebuilt!

If the heads were machined that badly, check the rod bearings. Chances are good they didn't recondition the rods and you'll find wear related to twisted rods - edge wear on opposite sides of the bearing shells. You'll probably also see main bearing wear indicative of needing a line-hone aka twisted block. And its always possible they didn't remove all the core plugs and left grit in an oil passage somewhere. If you see one shortcut, expect a few more...