What do these spark plugs look like to you?

I think they look hot. Are those Delco plugs? (I personally don't like them)

 

the problem is you got a GM plug in it



throw a new set in it and see if it goes away.

 

Honestly, switch to Autolite plugs!
AC Delco and Champion plugs are at best unreliable.
I have had a problem with both and when I contacted the tech department I was told to heat them with a torch before re-installing them so the resistance would go down and conduct a spark..... RIGHT! I have never had a problem with Autolite plugs in any vehicle.

 

I use these plugs because the amount of threads does not intrude into the cylinder, nor does it leave a partial thread not filled.

I posted a thread years ago describing how the number of threads of the plug EXACTLY filled the head, not leaving a half a thread un-filled, or a half a thread exposed into the cylinder.

The argument at the time was that if there was a little bit of thread sticking into the cylinder, it would catch carbon and strip the threads out when the plug was unplugged later on. And if the plug had half a thread less of the threads in the head, carbon would build up in that last half of the threads in the heads and eventually cause a problem if different plugs were used.

These AC plugs filled the threaded area of the GT heads without leaving an unused thread on either the plug or the head, so I used them.

Since nothing I do is without some sort of experiment...http://mmb.maverick.to/showthread.php?t=44638&highlight=gt40

 

that's my favorite quote! so you might get shocked, but you shouldn't get shocked!

 

Those plugs look quite normal. If you had blown a head gasket, you'd have coolant being pushed out the spark plug hole when cranked with the plug(s) out. I'd suspect if anything, you sucked in an intake gasket. Look at the area where the intake meets the head and see if any of the gasket top portions are missing. Loose intake bolts combined with reving it too high, then letting off in gear will do it. My son did this to mine after a 7500 rpm runup in 2nd gear when my 331 was in my 89 Ranger. A quick test with spray carb cleaner with the engine running will confirm a sucked in gasket.

 

Oh, and 250*F is NOT hot enough to blow a gasket, unless the coolant level is too low. Mine regularly gets that hot. What heads are you running ? Aluminum or iron ? Iron heads will go hotter before blowing the gasket.

 

AC delco always fouled up for me even Autolites didnt work for my 72 Comet GT for some strange reason, I had my best luck with Champion plugs.

 

Actually, that suggestion is true for soot fouled plugs, but you want a high shunt resistance (like over 800 Mega-ohms).

Soot forms under many conditions and can accumulate on the plug. Spark plug tip temps below 650degF - you're ok. Soot stays non-conductive. Tip temps between 650 and 900degF, soot can become conductive and shunt the spark to ground (misfire). Above 900 to 950degF for a spark plug tip temperature, the soot will burn off, and problem is solved. So, "torch it" (get above 900F) to burn off the soot.

However, this fouling should not be a problem if you're not running too rich, not too retarded, have the correct heat range plug, use decent fuel lower than 25% or so aromatic content, and have a drive cycle that gets your tip temps up on a regular basis. (Of course, too hot is bad also for other reasons.)

Anyway... It sounds like they may have just been talking out of their @$$ to get you off the phone, but what they were referring to may have been based on sound principles. And if this had been the problem, you'd be able to tell just by looking at them. I've never heard of "torching" plugs for any other reason though - although I guess I do learn something new every day.

Lastly, for the OP, those plugs look fine to me.

 

Likely a dead Delco plug. Done dozens over the years. If you test the plug you'll likely find its firing way up inside the plug. Old Fords seem to eat them up. Throw a new set of autolites in it and give it a try. I'm a firm believer in factory plugs for each make.

 

Mach'er,
These were new plugs - run for less than 10 minutes - and it didn't happen just once, we have this happen with several vehicles over and over. No soot - the plugs hadn't even changed color yet. The Champion rep came to show us that the problem wasn't with the plugs. He spent 3 days showing us all the different things that could cause this and made many calls back to the engineering staff. When he pulled out the oxy-acetylene torch to heat the plugs I pulled out a set of Autolite plugs. I put mine in and the engine ran fine. He heated the champions up and they ran for another ten minutes. Tried the same process in an LPG powered engine with the same results - Champions failed after a few minutes and the Autolites kept going. My boss got them to take the cases of plugs back and we bought Autolites from then on. We later switched to NGK plugs but I decided that the difference was negligible and have stuck with Autolite plugs every since. No problems in any of my engines. (2 years between tune-ups)

 

Another way to see if the cylinder is firing is to spray a little (spray bottle)water on the exhaust manifold as it comes out of the engine and see if it steams up. The one that doesn't is the one that is not firing.

 

I stick with the Autolite plugs as well as a Ford guy. But I do wonder what he was doing from a technical standpoint. Was he evenly heating the things, or targeting a particular surface of the plug - or were they still installed in the motor? Call me a nerd, but I like learning new things.

 

I have a whole other set of new plugs. I need to swap that #4 out and see if it runs better.

But we are supposed to get nasty weather tomorrow, with a chance of snow, so it may be a few days before I get a chance to try it out.

Oh, and thanks for that suggestion on spraying the header tubes to find a dead cylinder. Never thought of that.

I guess I could even buy an infrared thermometer, and even if it was firing part of the time and getting hot, that one cylinder would be cooler than all the evenly firing cylinders.

 

That would work. Those things are damn handy to have around anyway.