Plug burn

[Wolf Spyder]

Take a look at the photo and tell me what might be causing this odd burn pattern. The area to the right on the ceramic base is a much lighter color.

I have a flamethrower coil and the plugs and wires have only about 550 miles on them. Eventhough they look oily a white cloth at the exhaust shows no oil and I've not had to add any.

http://opelgt.com/photos/showphoto.php/photo/5318

[jeff denton]

I had that happen with a 350 in my Blazer "yard tractor". Just on one cylinder. Turned out to be a head gasket failure, coolant was leaking into a cylinder. When it got so bad it hydraulically locked I changed the engine, later tore down the core and you could see the leak on the head gasket.
So to answer your question, my opinion is that you are "burning" some antifreeze.
Do you get air bubbles in your radiator? Is coolant disappearing?
You might try checking head bolt torque, there was a thread about this recently.

[Wolf Spyder]

No bubbles that I've noticed. It looks like this on all 4 plugs and I've haven't had to add coolant. But, I'll check.

[soybean]

Originally Posted by jeff denton ......You might try checking head bolt torque, there was a thread about this recently.

Wolf Spyder Here's the thread Jeff was speaking about. http://www.opelgt.com/forums/6a-engine-mechanical/5824-head-torque.html
Jarrell

[tekenaar]

Looks more like plug oil burning deposits to me, especially since same in all cylinders. Most likely, worn valve guides if higher mileage engine and its been left setting without running engine for extended period of time. Original valve seals were never that good anyway.