I recently had a L98 rebuilt with all new forged internals and a stroker crank. Running just under 10:1 compression. The heads are brand new AFR 195 eliminators. I broke in the motor with Joe Gibbs 20x50 standard non-synthetic as that is what my engine builder recomended. I changed out the oil at 500 miles and again at 1,500 miles with the same oil. I now have around 3,000 on it.

While fixing an exhaust leak the other day I pulled the #1 plug to get to the header bolt and it is caked with ash deposits. But it looks like it is only on half of the plug so from some research it kind of sounds like a valve guide. However on cold starts I dont see any smoke out of the tail pipe in tradition of leaky valve guides. So I started checking all of the plugs and the only ones with ash deposits are #1 and #2 cylinders. Just for curiosity I ran a compression test and these are the numbers that I got. Keep in mind that I am at 5,800 feet elevation as i've heard that can effect the end results.

Cylinder# PSI
1 145
2 152
3 145
4 153
5 150
6 156
7 152
8 155

So they are fairly even. The plugs that were in there are the NGK FR4's. I replaced them with some delco 41629's today, as well as switching over to some Mobil 1 full syn 10w30. Does this sound like maybe I just got a bad batch of petrol? Or more along the lines of a valve guide?

Here is a picture of the #1 plug although it was taken with a peice of junk camera phone. Any suggestions would be greatly appreciated!

 

Reminds me of a pair of Dart 180s that came into the shop a couple of years ago. The guy only had 1800 miles on them, but the bronze guides were barrel-shaped on the inside. Ended up replacing all 16 of them. I'm not saying that's definitely what you have, it could be a few other things. Have you called AFR? Talked to whomever did your block? The front cylinders do run the coolest, and thus should be honed a little different.

 

Compression numbers look good. Not sure why you are getting ash on the 2 front plugs, but how are the new plugs you put in? If they are doing the same thing, do what Atilla said and ask the people who did the work. Also, where were the exhaust leaks at?

 

you havent been running any race fuels? 110 octane or any leaded fuels? hard to tell by that picture but the plug looks dry not like a severe oil fouling but more like a severe carbon fouling... low cylinder temps

 

The exhaust leak was on the #1 cylinder head where it connects to the header. One of the bolts was loose and was blowing out there.

I have not been running any sort of race fuel or additives. 91 octane only. I havnt had a chance to get any miles on the car until tonight so in the mourning I pull the front 2 plugs and inspect them.

 

The exhaust leak may have done the damage to the plug. Let us know what you find in the morning. Did you replace the exhaust gaskets or just tighten the bolt?

 

Well I got about 100 more miles on the fresh plugs and oil. I pulled the #1 and #2 plugs and they have oil on the top part of the thread and then theres white spots that are starting to form on the end of the electrode. Yesterday while at a buddys house I started it up cold and I did see a slight puff of smoke out the pipes. So I am assuming that it needs new valve guide seals?

 

What color was the smoke? If blue you are burning oil. If white, you are burning coolant. Recheck that for color of smoke.

 

I just had a buddy stand behind it while I fired it up and it is NOT white smoke so that eliminates the coolant or a head gasket leak. I guess all thats left is the valve guide seals and or the actual guides. Is this a common occurance for brand new out of the box afr heads? Or did I do something wrong breaking it in?

 

Heads don't have any break-in time. If you got them new, I would take the springs off and check the side to side clearance from guide to valve. Use a dial indicator and see what your measurement is and that way you will know if the guides are bad. Also, if the smoke was black, you are running a little rich.