Oil spark plug thread

[sixpipe98]

Hi All,
I decided to remove two of the plugs today to see how my new carb tune was treating them. Both had oil on which was alarming. However, the oil was only at the base of the thread which makes me think the rocker cover seal could have leaked? I do remember taking it off recently to tighten a loose tappet without replacing the gasket which was dumb. I don’t see how it could be worn piston rings as the engine is sub 50k miles since rebuild and never smokes. I managed to get a picture of the cylinder head which seems to have some oil staining. Any ideas what it could be? I hope its not piston rings…. I’ve attached some pictures. Cheers, Sam

P.S it’s a ’73T

[Nine One One]

The plug is dry and electrode seems to be running a fairly decent mixture, is it the right side as you look in the engine?

if so oil could have been spilt whilst topping up, running down into the spark plug chambers.

[sixpipe98]

ah that does sound plausible. I took one from either side of the engine and they both looked the same like the picture. I did have both valve covers off at one point without replacing the gasket so wondering if it could be that.

[sixpipe98]

Just pulled another and again oil at the bottom, dry at the top

[Nine One One]

By the bottom I take it you are meaning the top of the thread by the hexagonal plug spanner end.

Yours look nothing like the pictures below

https://procarreviews.com/read-your-spark-plugs/

If they were covered in oil near the electrode you would also be suffering from misfires and associated problems from them not firing correctly.

[sixpipe98]

Sorry yes that's what I meant. No looks nothing like the picture and runs fine.

[sixpipe98]

Do you know of any other ways that oil can get on the top of the cylinder head other than a leaky valve cover gasket?

[Nine One One]

Best thing to do is put the plugs back. Then use some brake cleaner, and compressed air and clean out the orifice.

DO NOT do this without the spark plugs being in situ as you stand the chance of getting all sorts of crap down your cylinder bores.

The oil could have been there for ages, and accumulated over a period of time, from oil spillages, cleaning down the engine bay area with Gunk, or any other cleaner.

Clean the orifices out, and just see if it does fill up again. From the pictures it is only a small amount anyway.

[sixpipe98]

Ok thanks a lot, sounds like a plan