Spark plugs continue to shatter...

[J-Madd]

Mike Z, what I meant was all of the info you posted was great info, except the part about the gasoline. I didn't mean it sarcastically. I know you just overlooked that he was running alky.

[J-Madd]

im not 100% sure what is happening first, once it dropped the cylinder this last time it puked all the coolant out. Could it have been slowly burning coolant this whole time which was causing a hydraulic lock in the cylinder shattering the plug? Then the third time finally blowing the oring completely? Honesly i really dont think that i put new orings in the head.

 

That would explain the fact that the overall color of the cylinder wall and piston top and skirts and plug looks great.

 

Im open to anything, and mike z j-madd didnt mean anything at all towards you, he is a very nice guy and would do anything to help you. I believe he said what he did because you kept saying 'gas' in your post and that you would recommend to run a 50/50 mixture.

 

 

I think you found the answer. Puking coolant-leaky head gasket/oring. Sometimes it only leaks outward, sometimes it will suck coolant in. That is your problem. Coolant in the combustion chamber effectively increases compression (by displacing what would be air in the dome, making it act like a smaller cc dome.) That leads to detonation, and that is causing your problem. Like MIke said, detonation is the only thing that causes that.

[gotta_goatsfast]

I would have $aid exactly what J-madd ju$t po$ted. Although porcelian i$ very hard, a cold $hock from coolant hitting the plug could quickly cool it and $tart a crack, which then shatter$. Either way, I blame the coolant being in place$ it $houldn't.

 

$o $wap in $ome o-ring$ and fre$h plug$ and $tart that Ban$hee....$$$$

[locogato11283]

Haha. I $ee what you did there $ir..

[trex banshee]

I think you found the answer. Puking coolant-leaky head gasket/oring. Sometimes it only leaks outward, sometimes it will suck coolant in. That is your problem. Coolant in the combustion chamber effectively increases compression (by displacing what would be air in the dome, making it act like a smaller cc dome.) That leads to detonation, and that is causing your problem. Like MIke said, detonation is the only thing that causes that.

 

 

cool! we will give that a shot then. We are going to get a new piston dome and gaskets and NEW orings, build a leak down tester and give it another go.

 

thanks again,

Thomas

[AKheathen]

i can't disagree more about the spark-plug shattering from detonation alone. go grab one and hit it with the torch. not a bic lighter, but a torch. it can pop real quick. one thing i would be looking at more closely, especially after the first time chewing a plug, is the crank bearings, dome seat, head plane, and deck plane/surface. also, you can check your timing with a light, and such, you know?

[J-Madd]

Well, the piston hitting the plug could obviously shatter a spark plug also. Didn't know a torch would shatter porcelain though. How hot does porcelain have to be to shatter? Does an engine ever get that hot without detonation or preignition?

[okbeast]

i can't disagree more about the spark-plug shattering from detonation alone. go grab one and hit it with the torch. not a bic lighter, but a torch. it can pop real quick. one thing i would be looking at more closely, especially after the first time chewing a plug, is the crank bearings, dome seat, head plane, and deck plane/surface. also, you can check your timing with a light, and such, you know?

 

We've used a torch to burn crap off plugs before, like ones that are gas fouled. Never seen one "pop"

[WINDYCITYJOHN400]

i can't disagree more about the spark-plug shattering from detonation alone. go grab one and hit it with the torch. not a bic lighter, but a torch. it can pop real quick. one thing i would be looking at more closely, especially after the first time chewing a plug, is the crank bearings, dome seat, head plane, and deck plane/surface. also, you can check your timing with a light, and such, you know?

 

 

It's detonation.....It's almost always detonation. (I know, I've owned a Trinity motor...I'm an expert at Detonation issues. )

Everything you listed above other than crank bearings...comes back to a detonation issue. Why check timing?.....because if the timings wrong, it leads to detonation. Motors don't get crazy hot without a detonation issue. Guess what crazy lean leads to?....Yep, Detonation.

Air leak?.....Detonation. O-ring blew....from Detonation. A piston firing creates hundereds of pounds of force...detonation jumps into the thousands. If Detonation can cause a tight plug to back itself out of a motor....why can't you except that it will crack the porcelain? Coolant can hyper cool the plug and cause it to break. But the coolant wouldn't get into the cylinder without Detonation blowing the O-ring first. So airleak, or carb issue is your starting point. (NOTE: If it's a trinity build....Blame the Detonation on the domes.)

[gotta_goatsfast]

Its not so much the tempurature, as the rapid tempurature change that will crack porcelain. Heat it up with a torch real good and then submerge that baby in water... This is why I made the comment about a coolant leak being able to rapidly cool part of the porcelain.

 

And its better to clean your plugs with a wire brush than a torch. lol