The Stovebolt Site Forums The Shop Area General Truck Talk spark plugs fouling out??

I am running a 350 in my 55. Latley I have had two spark plugs foul out when I realy floor it!
The weird thing is that both times the electrode is curled over and touching the porcelain insulator in the plug. It first happened on #5 plug, then #6 plug. The plugs are Bosch/Platinum plugs and are 2 yrs old.
Im wondering if my pistons are some how hitting my spark plugs. If so why now?

Roger

Maybe carbon build up on pistons. Or REALLY loose rod bearings, but I think you would know the latter.

I don't think the pistons could hit the plug, but I'll bet pre-ignition or severe detonation could knock them out of whack.

Stuart

to clean the carbon off the pistons, i was told you can take a mixture on brake fiuld and water and pour down your carb. until the truck alomst dies, it will smoke, and stink to high heaven, but will remove carbon off the pistons. a friend of mine told me about this, said he had done it before, but i don't like the sound of it too much myself :confused:

but i would change plugs, put in some of the nice 3-4 prong plugs so if that helps, maybe get "shallower plugs" some that don't thread way way in

mikes 63-k10 that is my next step to get plugs with less threads on them............this just puzzles me why the truck is doing this now when I has ran fine for two yrs

I would try some different plugs but shure wouldn,t put in plugs with shorter threads. They would cause more problems. You can get plugs without the extended tip. The tip is recessed in the shell.

To me it sounds like a mechanical hit from a valve.

Tighten up the plug in the plug hole. Mark the plug so you can tell the direction of the tip when it is installed. It is probably lined up just right so the valve hits it.

Try another plug that lines up differently.

Add another spark plug washer to the ones that are "fouling"? Just a thought.

I've sprayed water into the carb of a running engine before to knock out the carbon. We'd have it running at high idle and squirt water into the carb as fast as we could and try to keep the engine running. It would puke out all kinds of carbon out of the exhauast. Make sure you do it outside though.

A possible problem it could create is chunks of carbon getting stuck in the valves, so I wouldn't try it on a whim, but if you definitely know you have a haevy carbon problem...you don't have much to loose.

I would check out the indexing of the plug first.

Diesel it.Pour d in a hot engine slowley and keep the rpm's to keep it running for about 30 seconds.then pour enough so that engine stalls. Let set over night. Start next day and take for drive. Will be hard to start. Smoke great.

Rogpatt, let us know what fixes your problem. I got a coke riding on the answer.

Builder i didn't know water worked to do that, and Beaver 53 the diesel won't mess up your engine/ carb?

Everyone I ask says something is hitting the plug. But it has happened on both sides of the engine so I am not sure whats going on now!

It's the valves making contact with the end of the plug. Try indexing them as I stated above.

I'm w/ Builder's suggestion; seems like only a hit from a valve could bend the electrode to touch the porcelain. His indexing tip is the way to go to prove the theory w/ no pain & all gain.
tomo

I looked at a cut-away of the SBC and It sure doesn't look like the valve could hit the plug unless it (the plug) was about a inch too long. Seems like the insulator would be the first fatality in a direct hit. Interesting problem!

Stuart

It is interesting that the pistons of the two that failed are on the same crank throw. Have you worked on you carb and lost any parts? Things like nuts can pop back and forth between cylinders and then out the exhaust. How's your compression on #5 and #6 compare with the rest?

I will be working on trying to figure out why my plugs are fouling out this weekend and get back to you guys on monday

And what are the final results Rogpatt?

Sorry for the delay guys!
I ran my compression tester on each cylinder and they were fine. So I then repalced my expensive bosch plugs with cheap auto lights, adjusted my timing and the problem has not occured aqain. I did not feel comfortable pouring water down my carb. I have ran the truck hard a couple of times and so far so good.
Now can you guys look at my new post "Timing my Truck" and see if you can help me out there!

Look what I noticed when researching "Summit Racing Street & Strip Multi-Spark Digital CD Ignitions". I copied and pasted a portion of what was on the web site.

The capacitive discharge systems create the strongest spark possible at full voltage, with multiple sparks below 3,000 rpm to improve starting ability, idle quality, and throttle response, (((((while preventing plug fouling due to cylinder load-up))))))).

The bending of electodes is not considered "plug fouling", that is an entirely different thing.