Diagnose This?

[Rayhill]

Here are pics of my Twin Turbo 350 SBC pistons.
The heads are World Products.
http://free.***boat.net/gallery/Gearhead_Garage/Motors_and_Drives/P1010194.JPG
http://free.***boat.net/gallery/Gearhead_Garage/Motors_and_Drives/junk.JPG
http://free.***boat.net/gallery/Gearhead_Garage/Motors_and_Drives/P1010201.JPG

[Mrs. Duck]

Hey, this is Ducky, I'm having login trouble.
That looks like a broken ring to me. Keep in mind it's not necessarily on that cylinder, stuf can fly across from another hole through the intake. It's possible that someone lost a washer or something down the intake manifold, but not likely. Either way, it's needs to come apart. Sorry to be the bearer of bad news... frown

[Infomaniac]

If not a ring I hope it is not a piece of impeller. The piston is peeled up on the left side at the ring land.

[058]

Ouch... eek! I've seen pistons like that before. They look just like the pistons I took out of my TT/BBF. Broken rings/lands and exited thru the turbos. Check your hot wheels as they are prob. trash.

[DUCKY]

Oh Yeah, I forgot about that. Pieces of the turbine wheels... OUCH!

[MikeF]

Maybe a ground from spark plug on the opposite side? frown

[HOSS]

Bet it was loud! Had someone put metal from a nibbler down my carb. ****ed up pistons, heads, valves. Check turbos GOOD! Good luck bro.
Gotta love those bench racers! They never learn!

[Nstigator74]

Make sure that all your valve guides are complete and intact. I had a guide come apart once, it made marks like that

[shockwaveharry]

Pop the valves out and check the seats. I don't know though... Maybe something fell in??? Are the compressor wheels OK??? Hummmmm... Check the seats.

[Rayhill]

You guys are scarin me with talk about a piece from the turbos gettin in there. I assumed it was a broken ring. A new job, christmas, and shitty weather has prevented me from getting more into it. I will definately check the turbos. The boat had the turbos on it when I bought it. This is a first for me with turbos of any kind.
It wasnt that loud. I was out with a couple of friends. Had just finished a WOT run, not long, just long enough to do a fly by a skiboat loaded with bikinis. My boat is a 1979 Carlson CV23 yellow with gold metalflake. It looks and sounds wicked bustin down the lake with the turbos kicked in. People must think someone is filming a James Bond movie. I slowed down to about mid throttle and was headed for home. Poof ! Didnt loose any power that I could tell. Low knocking sound.
Dam I cant wait til next year!!!!!!!

[Tom Brown]

It looks like a piece of ring to me too. Please let us know what it turns out to be.
I'll bet those bikini clad chicks are wondering where you are already. :)
-- Tom

[058]

If I didn't know any better I'd say the engine was pre-igniting. The pistons show signs of excessive heat and it looks like pieces of ring embedded in the piston. I can't tell from your pics but is the top ring exposed because the piston is peeled back? Pre-ignition will burn pistons, detonation will knock holes in pistons, big difference between the two. Either way you are looking at rebuilding the engine and curing the reason that got you here.

[flat broke]

I'm gonna go with 058 on this one Rayhill. One thing I wanted to clarify for your. The guys aren't saying that debris from the turbo got in the motor, they are saying that debris from the the ring land/ring failure would be passed through the turbo. You'll want to check your TURBINE wheels, not your compressors first. The compressors pull air from the carb or an air filter, not the motor. The turbine wheels on the other hand are subject to whatever comes sailing out the exhaust port. Either way it sucks, but there is more going on here than just parts breaking.
I don't think your system was/is intercooled if I remember right so your combustion chamber temps could get high enough to pre ignite under higher boost levels. Since its hard for any of us to say for certain by looking at the pics, find someone reputable in your area that can look over your parts in person to see what might have gone wrong. If you have some cylinders that haven't been damaged as badly, maybe they can get a better read off of your plugs (all the debris in the cylinder shown might make it tough) and point you to a cause.
Sorry for the bad break but at least it was found in the off season.
Good luck bud,
Chris

[motor_jet]

impeller

[Chaddyshack]

What do the cylinder walls look like??? Is there any severe marring of the cylinder where a ring might have come out???
If there is no marring in the cylinder, I'm thinking along the lines of something above the pistons.
Either way, you have enough significant damage that I'm sure the turbine wheels are damaged. They will need to be replaced even with "minimal" damage to them as they spin about 100,000 rpm.
My .02

[spectras only]

Rayhill , all I see is one bank of your block showing one piston beaten up by a ufo wink .I would remove the other cylinder head to investigate. A piece from a valve missing there could have ended up on the piston shown, they travel across occasionally :D .

[Rayhill]

Hey thanks for all the help!
Gonna jump in to it next week or two. After Friday I am off work for 2 weeks. I will be sure and take pics along the way.
Happy Holidays !!!! smilespi

[sdba069]

Doesn't look circular enough to be ring material,also doesn't look to me like guide or seat material.Possibly turbo parts,looks more foreign to me.Piston looked like it suffered from detonation,but it could be the result of mechanical damage from the debris.Would need a closer look to tell for sure.
Garry
P.S..Upon a second look,what looked like a broken ring lens,I think is just a shadow.Is the piston intact around the edge?

[Snowboat]

I'd say its turbo material. We see it in diesels all the time. Usually it wastes the intercoolers. Why would it be valve pieces. He's already looked at them when he got the heads off? For the rings to have gotten on top of the pistons, there usually is one that is eroded down past the land.

[spectras only]

Snowboat ,the shape of indentations on the piston looks like a piece of ring that might have flung around [the shapes are consistent in width and length before broke into smitherens creating the tiny dents].I've figured Ray already checked the turbo since he's got one head off,and he didn't say if he checked compression in the untouched bank.The piston shown seems to be still intact to let a piece of ring pass through though.Matter of fact I had a failure once when a small [1/2"long]piece broke away from a valve of the opposite side of the demaged piston .We're all just guessing I guess wink

[Jrocket]

Almost looks like a small needle bearing piece.Or a small pin from something....its ugly whatever it was.. :rolleyes:

[Rayhill]

Compression checked fine in all other cylinders. Only about 30 psi on the cylinder in question. It sounded like I had melted a hole in top of the piston. No sign of anything flying around inside the turbo box.
Have always been able to pull engines with my engine hoist. This boat is a lot higher than my CVX18. I am going to have to take it somewhere to have the block pulled.

[Rayhill]

Good news and bad news!
Bad news: My son left my digital cam. on top of his car and it is gone.
Good news: My engine problems are limited to one cylinder. I dont know how I missed it earlier, but up top in the shadows. I didnt see that the upper top of the piston completely melted away. You can see the crown ring. The cylinder wall is not severely marred at all. No sign of anything going through the turbos. YEA!!! Hope my heads check out OK?
Happy New Year everyone!
100th post!

[spectras only]

Ray ,sorry for the wrong start of the new year [lost camera :( ] ,but good news on the engine with only one piston demaged by detonation. I had a similar occurence once and after the piston replacement the engine still had lived a long time.Have a good trouble free new year :) .