Today I went to my dads house to let him borrow an Edelbrock 600 that I had setting on the shelf. He was trying it on his stock 283 in his 66 Chevy 2 wagon. This engine is stock other than a bigger cam and it has less than 10,000 miles on it. Anyhow after starting the car with my carb it ran fine for about a minute. Then the engine sorta sped up just for a split second a couple of times. It was like someone barely touched the gas then let off. I thought that was weird but we let it keep running. Then all of a sudden the engine starts knocking. It didn't sound like a rod or main, but more like something rubbing or a loud click. We shut it down instantly and stood there confused. We didn't restart it and we could tell it was coming from the passenger side. We pulled the valve covers and everything looked ok. So we then decided to pull the passenger side head. Upon pulling the head we found a tiny screw laying on top the piston. It must have came out the carb I let him borrow and got sucked down into the cylinder. The piston had one small spot on it. Its about 1/4 inch round and no deeper then .030. I guess its the size of the head of the screw. The head looked ok and he is going to pull the valves to see if they are bent. Other than the piston everything looked ok. The piston doesn't appear to be cracked or anything. My question is, and forgive me if its stupid, can this piston be reused? The engine didn't run no more than 20 seconds like this at idle. Is the strength of the piston now going to be stressed because of the spot on it? I don't want the piston to get a hole burned in it now. If a new piston is what it will take, then thats what we will do. I just feel bad since it was my carb that caused this. Thanks for any help or advice.
Joe

I had the same thing happen to my wifes 82 camaro (girlfriend at the time). The piston should be Ok. I would look it over well and also run the piston down the bore and check the cylinder wall for cracks. You wouldn't think it but it can crack the cylinder with the side loading, this is what happened to the 350 in the 82 ( it ran a bit longer and tossed the screw between a couple of cylinders, really impressed here). That is bad but I would think you caught it in time as long as there isn't a HOLE in the piston.

I know a guy who dropped the wingnut from his air cleaner down the carb, he started the engine and drove it around the block, all of a sudden it make a loud noise and started missing. He drove it back home and shut it off, pulled the plugs and found one plug that had a closed gap, he RE-GAPPED the plug and fired it back up and it ran fine. After about two minutes of running he heard a noise in the muffler, then the lost wingnut rolled out of the tail pipe all bent and deformed. The engine still runs strong, its a 350 in a 69 chevelle, this is a good example of why people shouldnt drink and wrench.

As for your problem, I would triple check everything and go from there. If all you have is nicked piston crown then count yourselfs as lucky, just debur it and slap it back together. I would also findout forsure exactly where the screw cam from, it could be from your carb or the old one that was on before or even from something else and it was just a radom accident.

Thanks alot guys for the help. We will check everything over good and put it back together.
Thanks again, Joe

I almost the same thing happened to me to a 66 chevy truck but with a 1/4" nut on my #1 piston put a small dent in the piston. It might have been fine but my engine only had less than 100 miles on it, I went head and changed the piston just in case. Was a lot more time than money to fix.

same thing happened to my 80 Z28 and i had some camel humps on the shelf it was the perfect excuse to put'em on droped my 80 Z from 10.20 1/8th mile to 8.84 1/8 mile! I think it had 624's

You would be better off to drop the pan and pull that one piston. I had a piece of porcelin come off a spark plug last year and rattle through 2 cylinders before exiting the exhaust. Bent an intake valve and collapsed the piston skirt and the top ring land, pinching the top ring. I fixed the head right away but the piston looked great so I didn't think nothing of it until I tore the engine down in the fall to find the damage.

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I think dad was going to smooth up the piston a little and put it back together tonight. I hope he gets it running and its ok.
Joe

<font face="Arial,Verdana" size="2">Originally posted by Joekool:
I know a guy who dropped the wingnut from his air cleaner down the carb, he started the engine and drove it around the block, all of a sudden it make a loud noise and started missing. He drove it back home and shut it off, pulled the plugs and found one plug that had a closed gap, he RE-GAPPED the plug and fired it back up and it ran fine. After about two minutes of running he heard a noise in the muffler, then the lost wingnut rolled out of the tail pipe all bent and deformed. The engine still runs strong, its a 350 in a 69 chevelle, this is a good example of why people shouldnt drink and wrench.

As for your problem, I would triple check everything and go from there. If all you have is nicked piston crown then count yourselfs as lucky, just debur it and slap it back together. I would also findout forsure exactly where the screw cam from, it could be from your carb or the old one that was on before or even from something else and it was just a radom accident.</font>
i too have seen this, it was a cam swap on a chevy p/u , one of the lifters came apart when pulling it out, and guess we didnt get it all out started with a knock we revved the p!ss out of it and somthing came flying out the exhaust, no more knock and engine is still running strong....

I went to a freinds house to see his new engine.I rapped the trottle ounce hard the motor made a horrible noise and shut off .
The carb came from the same place the engine came from.
Pulled the head a section of air cleaner stud was in the piston.Must have been on one of the secondary trottle plates.

We had to build a new engine.

Well, it was worse than I thought. His cylinder has a crack all the way down it. So the engine is toast. I can't figure out how the block cracked that bad, but didn't destroy the piston.
Joe

I am sorry to hear about your bad news. This is a classic reason why I never drive someone else's car. No matter what you do no can never repay them for any damage even if it was clearly not your fault. A modern day car with a warranty is one thing but a classic that has hundreds or even thousands of hours, never.

Wow, bad scene. I think Drgracr might still have his sbc shortblock for sale. check with him. I believe its been in the swap meet

I think he is going to put the original 6 cylinder back in until he gets another V8 ready. The 283 engine that was in it was mine at one time. When I went with a 350 I gave him the 283. The 283 had everything done to it as far as machine work. It sure is a shame a 5 cent screw did it in.
Thanks, Joe

Its amazing how much damage can occur so fast.

Well good luck

Dang, guess I got lucky. I lost a washer during a carb swap, and idled the engine for less than 2 min before deciding to pull the head to see what the noise was. found the washer crumpled up into a long slug, and a slightly dented up aluminum piston, but put it back together. That was probably 50-60 thousand miles ago.

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76 Camaro, Blue/Black, .030 350, M21, Z28 body parts.
90 4WD S-10 rustbucket snowbank reducer

You was very lucky. I'm still baffled at how the block cracked really bad, but the piston only got a small dent. It looks like the piston would have went before the block did.
Joe

Its freaky how the things can take the stress of running, but the tiny change in forces from something like that screw can distort and crack solid cast iron like it was glass.

At least it wasn't something super high dollar and irreplaceable like an original Z28 DZ302 or LS6. THAT would make ya sick! A run-of-the-mill smallblock is a pisser, but nothing that can't be replaced and be better than new.

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'03 Yellow S-10 4.3L - "The Bus"
'75 LT in progress again...

Its amazing you can run 6500 rpm and nitrous on an sbc all day long, and a little screw ruins things. That sucks!

<font face="Arial,Verdana" size="2">Originally posted by Joekool:
I know a guy who dropped the wingnut from his air cleaner down the carb, he started the engine and drove it around the block, all of a sudden it make a loud noise and started missing. He drove it back home and shut it off, pulled the plugs and found one plug that had a closed gap, he RE-GAPPED the plug and fired it back up and it ran fine. After about two minutes of running he heard a noise in the muffler, then the lost wingnut rolled out of the tail pipe all bent and deformed. .</font>

Kind of reminds me of when a pet eats a string and has one end hanging out both ends. But then I am tired right now http://www.nastyz28.com/ubb/smile.gif