Looking for advice on valves, lifters etc.

Jon O.

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1972 Chrysler Newport with 400 engine. Completely factory original with 80,000 miles on it.
I had a moment of teenage dumbassery when I dropped a screw into the exhaust port for the choke and couldn't find it. A week or two later it started knocking. I've started disassembling the engine, and that screw ended up lodged in one of the valves at the front passenger side of the engine. When I shine a flashlight into the port, I can see the screw head, and a round metal shaving in there. After it was knocking, the car was ran for about 3 blocks home, and I never started it again after that. What kind of damage is possible here?
Also, while I already have everything apart, what parts should be checked for wear? The bottoms of the lifters are slightly pitted from the car sitting for 20+ years, and I plan on replacing them.
 
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I cant get a good picture of the valve, but this is where i am. I haven't removed the cylinder head yet.
 
If the screw is up in the valve I would think the lower end is fine, just need to repair the 1 head hopefully. Yank that head off to see what the story is
 
1972 Chrysler Newport with 400 engine. Completely factory original with 80,000 miles on it.
I had a moment of teenage dumbassery when I dropped a screw into the exhaust port for the choke and couldn't find it. A week or two later it started knocking. I've started disassembling the engine, and that screw ended up lodged in one of the valves at the front passenger side of the engine. When I shine a flashlight into the port, I can see the screw head, and a round metal shaving in there. After it was knocking, the car was ran for about 3 blocks home, and I never started it again after that. What kind of damage is possible here?
Also, while I already have everything apart, what parts should be checked for wear? The bottoms of the lifters are slightly pitted from the car sitting for 20+ years, and I plan on replacing them.
You dropped it where exactly?
 
As noted, the screw is not likely to have gotten into the engine unless it fell into an intake port. If the engine is knocking, it is probably some other cause. Remove the oil filter and pour the contents on a dark rag to check for metal. If the filter is full of metal shavings, most likely a bearing has failed and you are headed for a rebuild. If the filter is clean, rent or borrow a bore scope and start checking the cylinders for piston damage. Your cam does not appear to show any abnormal wear, do not need to replace it unless the engine needs an overhaul.

Dave
 
That's the choke well. No way for the screw to get into the combustion chamber/valves from there. The exhaust crossover is also not an access point. That's a LA small block intake in your post, not a B engine intake.
That’s what I was thinking, no way unless you dropped it down the carb.
 
In '72, as I recall, there is a stainless steel cup into which the choke thermostat resides in. Remove that cup and gasket, and all that's underneath is the exhauast crossover passage between the heads The exhaust gas pulsations could easily cause that screw to travel between several exhaust ports before it finally stopped somewhere. Why was that stainless steel cup absent from the manifold? Just curious, but doesn't really matter now.

In order to see what's going on, you'll need to remove the affected cyl head to see what's happened and what it'll take to fix it. Possibly a new valve and install a new valve seat?

Might end up removing both heads. For good measure, the engine could well be close to needing a valve job anyway (from my family's experience on 383-400s). Hopefully, the knock is from a piece of dislodged carbon, but with the pistons being so deep in the hole, it would have to be a big one.

Hope you're going to do a new timing chain too?

Keep us posted,
CBODY67
 
I had the choke off because it wasn't doing anything and making the car very hard to start at times. One of the small bolt heads broke when taking it off. When I went to put it back on, I dropped one of the new bolts down the choke well. If it doesn't lead to the valves, where does it lead to? I've tried to find the answer in the FSM. I've shined a flashlight into the hole, but it bends so sharply that I can't tell where it goes.
I do consider that it could have been a coincidence that it happened at the same time, and it's a possible spun bearing. I've had odd coincidences happen before.
The day that the knocking happened, it was idling in the driveway and was running fine, but it had a faintly audible clatter/rattle sound. I got about two blocks down the road and the knocking started.
I will check the oil filter next. Thank you all.
Cbody67, I replaced the timing set 3,000 or so miles ago.
 
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No metal in filter that I can see. I'm in the process of getting the head off. The valve I saw a metal shaving in, the spark plug for that one is bent. I know it was not bent when it went in.
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something got in there, hopefully the chamber isn't beat up and the valve can be replaced and seat redone.
 
Might as well pull the head(s) and see what there is to see. I wonder if a chunk of carbon could be the culprit? I really don't know how a screw could have gotten into the combustion chamber or cylinder bore the way you've described it. But never say never...
 
Finally got the head off. What a pain. So much headache could've been saved by running a magnet down the hole...
The top of the piston, and the valves have a visible "hammered finish." It is the screw, I can see part of the threads. It bounced around and eventually lodged its self in the top of the piston. There is faint scoring on the cylinder wall.
What do you all advise that I do?
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Doesn’t look that bad. How deep is the scoring on the cylinder wall? No holes in the piston?
 
The deepest score line I can just barely catch with my finger nail. The next deepest I cannot. The chunks are the remains of the screw.
As far as I can tell there are no holes in the piston. The deepest pit is around 1/16 of an inch. I don't know how thick the pistons are.
I believe the knocking was caused by the lodged screw making the piston contact with the top of the cylinder head. If it continues after its all back together, ill check the rod bearing.
 
In no particular order: The head should be disassembled and the valve and seat checked for defects, the valve could be bent and the seat could be damaged from things bouncing around in there. The piston needs to have the top cleaned and be checked for cracks. It is also advisable to remove that piston and check the body for cracks and the rod for misalignment. There appears to be two small cracks or gouges in the piston head. The head should also be buffed to remove any sharp edges so that there will not be a hot spot on the head that would cause pre-ignition. The scoring on the block does not look that bad.

Dave
 
It now appears you are on the edge of "the slope". You can pull things apart and fix only what's got real, significant damage . . . or do a complete rebuild, valve job, etc.

Some "shade tree diagnostics" might be appropriate. For example, pour some solvent into the port of the affected valve to see if there is leakage past the valve seat. A wire brush on the end of a drill motor can help clean the surfaces to see what's under the existing coating of carbon and such, followed by a "crack-check" operation appropriate for the material being checked.

Please be aware than anything you disassemble will show some wear on it, but that doesn't necessarily mean it's "worn out" per se.

Do remove the affected valves for inspection, replacing as needed. One of the "while you're there" things woudl be to put all new valve seals on the valve stems, though. Which should be in the "head set" gasket set along with the head gaskets and other related gaskets/seals.

As for the piston, it might have survived, just with the new "finish" on its top areas. BUT that might require complete removal to determine that.

The knock? A main bearing knock and a rod bearing knock have different characteristics as to when and how they "knock". Check a MOTOR Manual (or similar) for those diagnostics. Which are different knocks that "piston knocks" (usually related to piston-cyl wall clearances).

Back when our '66 Newport was a "used car", I got in it one afternoon and motor started to knock. Oil light was NOT lit-up. The knock was not related to engine load and was consistent with engine rpm. I eased it home, then eased it to the dealership, then back again. About 3.5 miles all together, at low speed/low throttle easy driving. The service manager said it was probably a piece of carbon that had come loose. He suggested puitting a quart of Rislone through the carb to soften it up a bit, so it'd crack and go out the tail pipe. While at the dealership, one of the techs talked about a carb base nut getting into the intake manifold. He said it made a big racket, going from cyl to cyl before it finally was embedded "somewhere". He said that when they pulled the heads, there were pock marks in seeral cylinders from it banging around.

Next day, no more knock. All was well and no more issues . . . all the way to 150K miles and past. Your experiences might vary.

Take care and keep us posted,
CBODY67
 
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