I think God doesn't want me boating....

in most carb'd engines you likely will find the flow of the gas/fuel mixture will not be evenly distributed among all the cylinders due to the natural flow of the intake manifold....the designs of the manifolds are just inefficient this way....some designs are better than others...it is very possible to have have one or two cylinders running leaner than the others due to this....thats just one big advantage of fuel injection directly into each cylinder over carb's....

you may want to inspect the intake manifld to be sure nothing is obstructing the flow of the gas/fuel mixture such as a bad mold casting that did not get trimmed off.....

good luck....


cliff
 
Maybe because I'm nuts but it sure looks to me like other cylinder in this pic is all marked up directly below the plug. The fact the hole is clearly lined up with the plug I would go with ignition issue. To hot, to cold, inconsistent spark and the list goes on. I know when I'm up to plane with my twin 4.3s all i can hear is there buzz, I don't think we could hear any noise made by an engine about to let go. You mentioned thunderbolt ignition. I assume this is an aftermarket addition? One thing I've learned is to never change ANYTHING from stock on a boat unless you have a DEEP wallet, lots of time and prefer spending time in your garage over being on the water.
With all that said, good luck and if there is anything I can do to help let me know.
 
If this didn't suck so bad I would say it's karma from posting those glamour shots for the calendar. Seriously though, you should be happy that you are mechanical and can most likely rebuild the engine fairly easy as long as the cylinder walls are acceptable. I would recommend that you pull the heads on the other engine just in case though. Throw some money at it now and live to boas many, many more days!
 
Update: So I had 2 different mechanics that I know come at two different times today to give me their thoughts....People I know that work at some local shops, called in some favors since I did some electrical work for them. They "Both" gave me the exact same opinion. They said, " All the other cylinders looked fine, the spark plugs looked perfect. Not Lean, not the fuel, not timing." Ready for this, "Spark Plug Failure." They both said everything looked way to good. So in a form, it was "Detonation" (uncontrolled combustion) but due to the plug failing. Said it happenes more often then not with cheap plugs, they were surprised that this happened with NGK. There was infact no continuity on the number one plug....Maybe it is Karma, those were expensive plugs too and they are only 3 years old.

I was also told that I shouldn't replace just one pitston, but do all...My luck GM changed the style of these pistons and the new one's are a bit different then these old ones.

No damage to the Cylinder walls, and should be able to just get away with Honing them.

Heads are good, but need to get sent in for cleaning, possibly port and polish.

The pistons are $200 a pop and thats just a wrist pin, piston, and rings...
:wow:


SO, started tearing the engines completeley down, putting all parts, and bolts into labled baggies, and then all big parts into totes, this is going to be a drawn out project, as I'm pricing things now and looking to be about $2,000. for this overhaul. May have to wait for a tax return on this one....

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.:wow:
 
Wow, good luck Stace, hope you can get everything under your prospective price...
 
Man, You don't f**k around!! Get right into that sh!t!! Good luck with the rebuild. Keep us posted on your progress!
 
So check this out! Just did a search on google about Iridium plug failures.....I'm not alone, and the results in the automotive world are similar....Wonder if I should get in contact with NGK about this. The plugs I'm usuing is the reccomended plug by NGK for this engine....:huh:
 
As promised, but sounds like you got it sorted

ImageUploadedByTapatalk1355216411.114926.jpg
 
That's some new info for me.....plug failure. Hmmmmm....hope it's a rare occurrence, Mike.
 
rcon said:
As promised, but sounds like you got it sorted

View attachment 28325
Click to expand...
that is very obviously a detonation issue...it is blown out
you can see the edges of the hole are broken
Stace...yours appears from your pics to be melted through.
I still hold the opinion of a lean issue causing a hotspot...like on the cylinder next to the burnt piston.
have the heads and valves pressure tested and the intake manifold.....there is air getting into that cylinder leaning the mixture.
I have seen plugs crack the ceramic around the tip and tear up pistons but you should find a piece missing.
you should not have that hot spot in the center of the piston top on either cylinder as in the first picture.
 
moparlvr4406 said:
that is very obviously a detonation issue...it is blown out
you can see the edges of the hole are broken
Stace...yours appears from your pics to be melted through.
I still hold the opinion of a lean issue causing a hotspot...like on the cylinder next to the burnt piston.
have the heads and valves pressure tested and the intake manifold.....there is air getting into that cylinder leaning the mixture.
I have seen plugs crack the ceramic around the tip and tear up pistons but you should find a piece missing.
you should not have that hot spot in the center of the piston top on either cylinder as in the first picture.
Click to expand...

Absolutely +1 Jim. A misfiring plug is not going to cause a lean condition - but a lean condition could (will) cause a misfiring plug & of course detonation. Also, at $200 a hole, you could put some decent forged pistons in there - and buy a bit of insurance....but as Jim suggested, there has to be something else going on here - get a good close look at that intake manifold gasket, if it's still around.
 
That spark plug just looks so clean? Not loaded up or burned up. The color/temp of plug looks perfect? It certainly was a fast event/failure and not a slow death. Looks like an instant failure of the piston. It has to be something other than the plug just failing, Mike.
 
Good luck Stace.
Sorry to see that, but I know you'll get her back together. Remember you could take a month getting her back together and there are several poor soles here that stilll wouldn't be able to go boating for 3 more months.
 
Engine is back together, and running. Goes back in the boat tormorrow, hopefully sea trialing on saturday....God Willing!

All new Sealed Power Pistons and Rings
New Sealed Power Tri Metal Cam, Big End, and Main Bearings
New Sealed Power Intake/Exhaust Valves
FelPro Valve Seales
All new gaskets, O-rings, and Seals (Marine Grade not Automotive)
I Did a semi half @$$ed Port and Polishing of the Intake Manifold and the heads
Lapped The valves
Polished all sealing surfaces
Plasti-gauged the Main Bearings and Big End Bearings
New Spark Plugs

For a grand total out the door....$986.54 just for engine materials (Doesn't count all the brake cleaner, sanding materials, RTV, Oil ect.)

Here is a link to the video: https://www.facebook.com/photo.php?v=10151344997452038


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Ouch!. Sorry to hear about the issues. 2 positives; At least you can do the work yourself, and its early in the season, so you can still rebuild and enjoy the summer.

Keep the faith and "Break Out Another Thousand", or 2.
 
Stace, glad to hear you are getting her back together. good luck on saturday man!
 
I am just happy to see you painted that timing chain cover it was really bothering me.Good luck on the run
 
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