Spark plugs: seven tan and one nasty black

[Dimi Terleckyj]

Provided the head gasket and inlet gasket is intact the only way excess oil can enter the cylinder is either up past the rings or down via the valve stems.

In a new engine the piston rings and oil control rings shouldn't be the likely cause unless one was damaged during installation by the engine builder.

The valve stem seals are usually a metal collar with the rubber seal vulcanised onto the metal collar.

They normally dont split but can be damaged by not seating them squarely when installing.

The other problem with valve stem seals is they dont always remain down over the top of the valve guides and can float up and down on the valve shaft as the valve moves which can appear they are seated but while they are up will allow oil down into the cylinder.

Either way the only way to confirm is to pull the head and remove and replace the seal.

Dimi

 

[Russ Noble]

Chuck,

If its a stem seal its a relatively simple matter to pull the rocker cover & shaft assy & replace the seal using a KD tool & a piece of nylon rope /cord.
Jac Mac

Dimi/Chuck,

Listen to Jac Mac, he's saying you don't have to pull the head off to do the seal!!

It's common procedure for switched on guys like Jac Mac. He's told you how to do it, if you're unsure and need the gaps filled in I'm sure he'll oblige.

Cheers

 

[Chuck]

I believe the problem has been discovered.

Upon pulling the valve cover and carefully looking at the intake manifold gasket, we discovered that the portion around intake runner #2 was moved outward about a quarter inch. The impression from where it had originally been placed was visible. What appears to be a rip in the gasket is visible on one side. The gasket holes are not centered on the manifold bolts. So it looks like we will be replacing the gasket.

In the first picture, the upward movement of the Felpro gasket is apparent. In the second picture, what appears to be a small tear is visible.

Any ideas why the gasket would fail?

Replacing the gasket would seem fairly straight forward, albeit time consuming. Any tips or recommendations would be welcomed.

Thanks to all for the good analysis and tips and suggestions.

Chuck

 

[Jac Mac]

I believe you already have the answer over on CC Chuck.
Once you have the manifold off post some pics of the old gaskets and valley corks if fitted.

Jac Mac

 

[David Briggs]

Check the shoulder length of the manifold bolts, you may not be fully torquing the intake, allowing the gasket to move.

 

[Chuck]

It has been a while since I reported on the problem with the 427. As we know, the problem was determined to be the intake manifold gasket. The Cobra has sat in the garage, idle, while other tasks preoccupied my time.

The Genesis engine was actually built by Woody’s Automotive, Thorntown, Indiana, a few miles north of Indianapolis. With Run and Gun rapidly approaching I was getting anxious to get the intake manifold gasket replaced. On Monday of this week I called Dennis at Woody’s Automotive and he graciously agreed to travel the four and a half hours to my home on Friday to check the engine.

Friday afternoon was warm but the humidity was low: a good day to work on a Cobra. In a couple of hours time the job was accomplished. Not only was the gasket on the starboard side badly distorted with a quarter inch opening by cylinder 2 (the one with the oil problem), but the gasket on the port side was also deformed and likely would have soon failed as well. Looking at those gaskets it was a bit amazing the car ran as well as it did.

The Felpro gaskets were replaced with gaskets that have a steel inner layer, so hopefully this repair won’t need to be repeated.

One wonders if the manifold bolts may not have been torqued sufficiently.

We opted to put the "Cobra" air cleaner rather than the turkey basket back on to make it easier to adjust the carb.

I will report further after the car has some more miles on it. Thought it best to let the sealant set up thoroughly before running the engine more than necessary to adjust the timing and carb.

Thanks to all for the excellent suggestions that led to the solution.

Dennis at Woody’s Automotive deserves special recognition for going way out of his way to accomplish this repair and doing it on such short notice.