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383 40 Stamped Pistons and Corrosion

RockyPat

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Hello everyone,

I have a 1969 383 R stamped non-HP motor.

I got it for free, as it had been sitting outside for a while. Water got in it, and it’s stuck.

I used a wire wheel to get rid of the rust and grime to see the condition of the cylinder walls.
To my surprise I noticed that the pistons are flat tops with “40” stamped into them. I don’t think these are stock pistons. Someone must have rebuilt this engine at some point.

I assume that this means the engine has been bored 40 over. Am I correct? I do not have a micrometer, so I haven’t measured the bore yet.

I was thinking this engine still had its stock bore, and that I would be able to bore it out to clean up the cylinders.

2 cylinders are very bad and the other 6 are not bad.

With the block possibly being 40 over and the condition of the 2 cylinders being this poor, do you guys think this engine could be bored 60 over and saved?

I could sleeve the 2 bad cylinders, but I don’t know if that makes sense when I can pick up another block for a few hundred dollars.

Let me know what you guys think!

Thanks!
 
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Yes they would be .40 over pistons.
You need to see what the machine shop determines as far as cylinders condition.
See what the bottom end looks like.
Cost wise may be better to find another engine
Price it all out first and see what’s the best for you.
 
Take it all apart and let us know what you find and I’m sure you can get good recommendations on what to do going forward.
 
If you got it for free your already ahead of the game. Tear it down completely then take inventory of all the parts that are good. crank and rods may be fine or junk. Dont waste money on the block if a better one can be found that needs less work to make it right.
 
New block, for sure. Then you know what ya got, and don't have to wear a blast suit every time you want to put your foot in it.
 
From what I've heard/read most 383 blocks can easily take .060 overbore. Only the machine shop can tell you if that's enough. You may want to sonic check the wall thickness. Check the crank & rods to see how good they are. I always check the crank with my home mag check, stand the crank on end (balancer off), tap each counter weight with a hammer, see if it rings like a tuning fork. If it sounds dull, the crank is junk. If the rods have any discoloration, they are junk. Mopar bottom ends are generally real tough, unless they have been abused. I have worn out several 440 steel cranks because of high (7000 plus) rpm.
 
..,those wall are pretty badly pitted sir. Lots of 383 out there in way better shape for not a lot . Machine work on that will be sunk cost sir.
 
Thanks guys for the comments! I will keep on trying to free the engine and get the crank and rods out and inspect them. I will also try to have my machinist take a look at the block to get his opinion soon.
 
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