8N piston and ring questions

boler76

Member
The engine is a '49 8N, The bore measures 3.22" the pistons measure 3.2", I need a piston as a ring gland is missing and I need a full set of rings, What oversize piston do I need and what Oversize rings do I need to fit these pistons . 3/32" comp and 3/16" oil grooves. 4 ring pistons. Thanks for help.
 
(quoted from post at 05:37:48 10/09/12) The engine is a '49 8N, The bore measures 3.22" the pistons measure 3.2", I need a piston as a ring gland is missing and I need a full set of rings, What oversize piston do I need and what Oversize rings do I need to fit these pistons . 3/32" comp and 3/16" oil grooves. 4 ring pistons. Thanks for help.

I would put in a new sleeve, piston set and be done with it. Original bore was 3.100"
 
(quoted from post at 13:37:48 10/08/12) The engine is a '49 8N, The bore measures 3.22" the pistons measure 3.2", I need a piston as a ring gland is missing and I need a full set of rings, What oversize piston do I need and what Oversize rings do I need to fit these pistons . 3/32" comp and 3/16" oil grooves. 4 ring pistons. Thanks for help.

Exactly what Geiger wrote. Go a looking for a new set of sleeves for it if it's out that much. Now you need to figure out what sleeves it has in it and get them pulled out. http://www.ytmag.com/cgi-bin/store/...mp;cat=Engine Pistons and Sleeves&r=mcats That is an entirely different matter.
 
another question, due to fact that there are oversized pistons in the engine already, how does one tell if the block has been bored out and oversized sleeves already put in??
 

About the only way that I think would be reliable would be to pull the sleeve and measure the bore. assume you have cast thick sleeves and not the thin steel ones.
 
more questions, from my search I find that the original OD of sleeve is 3.368 if they are original sleeves, they are cast, the measured ID is 3.22" does that leave me with .075" wall thickness, if so why would I change sleeves when I have .030" oversized pistons and this site sells them, Could I not just replace the one bad piston and use oversized rings again? I am not a mechanic, I am an old retired electrician, so need all the help I can get Thanks.
 
Could I not just replace the one bad piston and use oversized rings again? .

Yes , that would be an option .

I would want to weigh the new piston and balance them all to the lightest of the four . Digital scales are cheap these days .

If money is not too tight , I would go with the .0825 over pistons and have the old sleeves bored in place for a fresh tight fit .

Chances are the .030 pistons will be loose , at least 3 of them . if you could swing it for a set of 4 new .030 pistons you would know that they all weigh the same and will have about the same clearances .

Basic rule of thumb is to keep everything equal as in all loose or all tight etc , just depends on cash flow .
 
I assumed that because they appear to be bored oversize and don't think that would work with 040 steel sleeves, but then I have been wrong a few times.
 

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