While checking and re-torquing my spark plugs a few thousand miles after getting new valve seals I noticed my number 1 plug looked different than the other 7 which all looked near perfect. It looks like I’m getting oil on the plug but only one area? The car is an 88’ GTA with 93k on a L98. I have no smoke on start up both cold and hot, no smoke while accelerating and deceleration and it doesn’t burn hardly any oil (less than a half quart in 3k miles). The car runs really good but oil on a plug can’t be good. I just want to know if maybe my new valve seal on number 1 is defective? Or maybe I have just one worn valve guide? Any input is appreciated.

These were a thousand miles ago:








I cleaned the plug up a bit and drove about 200-250 miles and this is what it looked like afterward:

 

Most of the time, what you are seeing indicates that an excessive amount of Engine Oil is being burnt in that Cylinder (Gasoline Burning Engines).

 

Valve guides? It doesn’t burn hardly any oil

 

What are they gapped at?
Also looks to me like they could use a little more timing, just from where im used to seeing the strap mark.

 

Timed at 8 BTDC and it’s at .45 gap as per AC Delco rapidfire instructions

 

Sounds pretty much in spec. Im just saying, if its happy at 8* no problem, but if youre like me and cant leave anything alone, id bump it up a little and see if it likes it.
But yea, looks like a little oil is burning in there from somewhere.

 

Lol I can’t leave well enough alone but the car ran best at 8 and didn’t like 10 or 12 as much.

 

Sweet. Yea, its like if the car is running well, i cant have that, i gotta find something to "fix"
.

 

Here is number 3 plug and it looks good to my eyes:

 

My number 8 plug has looked like that for about 50k miles. I take it out and clean it when I get bored. Might be something with the rear cylinders?

 

That is reassuring, I likely won’t lose any sleep over this then.

 

Wait, this was your number one plug? I read your post wrong I guess. Maybe a different deal but I still wouldn't worry too much on it at this point. How old are those plugs? Center electrode looks rounded some.

 

Number 1 plug and 10k miles give or take, I threw on a new one a few weeks back.

 

I was thinking maybe I got a bad valve seal or it’s not seated all the way? Just seems odd that only 1 plug would have the oil deposit. I was also thinking of going back to good old ac Delco r45 plugs as opposed to the rapidfire #2 on there now.

 

the engine tilts back, if the oil return holes at the front and back of the heads are gunked up, it will burn oil when the oil level goes over the valve seals, it uasally starts from the back...I got my camaro for $250 because of that back when I was 17, my dad didn't say a thing to the guy but tons of blue smoke out the exhaust, the seller thought the engine was done and needed a re-build, but my dad knew exactly what was wrong... turned out the return holes were gunked up, we changed the oil and took a shop vac with a piece of heater hose with some duck tape wraped around it shoved in the vacuum hose to make it fit and sucked out the oil return holes, it stopped burning oil instantly, it ran great

 

btw I still have that car to this day, it no longer has that 305, its now a 383, but its a survivor, it been through an EF-4 tornado and more military moves than I can count....never getting rid of it

 

Thats the weird thing with this is no smoke or oil consumption, I had this down to the lifter valley and it was squeaky clean. That’s awesome you got a deal like that and had an easy fix. I bet that stroker motor moves.

 

I really am leaning to that jacked up plug gap not being enough to burn off deposits and maybe a valve guide is leaking a little, after all this is a SBC lol.

 

it did when it ran, it hasn't been right since the tornado, i think the computer got damaged (edelbrock pro-flo 2) it was in Arkansas and it sat 6 months outside with no hood so the engine filled with water, we did a quick partial re-build (it only had 500 miles on it since the rebuild that converted it from a 350 to a 383, and its a 010/020 block that's was already .040 over...new bearings, polished the crank honed the bore, sleeved #6 bc something mechanically damaged the bore...still don't know what did the damage....gouges too deep to hone out, nothing foreign in the cylinder, rod straight) but it hasn't run properly, its been out a second time since, and gone over, everything looks good and it runs great on the test stand with a 750 carb, so its most likely the efi. I have a pro flo 4 kit sitting in the garage, and when I get a chance I plan on putting it on

 

Just wanted to update this thread, with the outstanding warm and dry fall weather in my area i I must’ve put on an additional 600 miles or more since I replaced and properly gapped that number 1 cylinder plug. I pulled the new plug and it looks good so far and I will chalk it up to either a bad plug or the too narrow of a gap that it had before.



Looks much better than the old one.