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Discussion Starter · #1 ·
i just got my cylinders back from machine shop and i supplied them with the pistons/rings.while testing the rings in cylinder(off piston)there is no end-gap and everything i've read says that there should be,and replace if over so many thou. of an inch.does anyone know if i have something wrong or should trust machine shop and install?
 

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DONT install as is- you need to set the ring gap to spec- if ring gap is too tight you'll scuff those cylinders the first time you warm it up.
 

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By the way, setting the ring gap is usually done by the motor assembler, not the machinist. At least that's how I've always done it.
The machine shop probably didn't even look at your rings.
 

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Hi tjwsuperxracer
The piston rings ends can be filed to give the correct end gap. That your machine shop did not do this for you or tell you that you should do this bothers me.
I would check that the piston to cylinder clearance is correct. Or have some one not connected to the machine shop and that I trusted check it.
I remember reading an interview of a top engine builder years ago. He said that his job was as a quality control inspector.
TomC in Ohio

tjwsuperxracer said:
i just got my cylinders back from machine shop and i supplied them with the pistons/rings.while testing the rings in cylinder(off piston)there is no end-gap and everything i've read says that there should be,and replace if over so many thou. of an inch.does anyone know if i have something wrong or should trust machine shop and install?
 

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Sensei
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The rings MUST have an end gap.... Otherwise, when they get hot and expand there will be no "room" and they will/could break, not to mention damage the cylinders.....
The specified end gap is based on the differing expansion rates of the piston, rings, and cylinder sleeve, so "theoretically" it is zero (or very nearly zero) only AFTER/WHEN everything is at operating temperature... BUT, cold there shoud be one.... AFTER you check that piston to cylinder clearance is correct, carefully file or grind to specs....
Make sure the ring is "square" in the bore when measuring gap.........
 

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Discussion Starter · #6 ·
i did and it was square in cylinder.how do you check piston clearance,or find out what it is?my manual does'nt have that in it.also,does .003-.005 sound right.book says replace if over .012.that's all info my book has.if someone knows where i can get a good manual i would appreciate the help.thank you
 

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Discussion Starter · #7 ·
also,i had my cyliders bored out to 497cc.i bought a kit that had pistons/rings/pins and head gasket as well.does this change gaps/specs on anything.i wanted a little more umph from my motor but this is getting expensive.
 

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Hi tjwsuperxracer
The specifications should have come with the kit. The stock specifications are for stock components. The stock specifications may work but may not. You have put money in to this that you want to get some value from. Find the correct specifications for the parts that you are actually using.
TomC in Ohio

tjwsuperxracer said:
also,i had my cyliders bored out to 497cc.i bought a kit that had pistons/rings/pins and head gasket as well.does this change gaps/specs on anything.i wanted a little more umph from my motor but this is getting expensive.
 

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Personally, I've never heard of any overbore kits coming with their own spec sheet for end gaps, piston to cylinder clearances, etc....


GB :mrgreen:
 

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Usually aftermarket overbore kits will supply you with specs for their pistons. The ring gap specs are usually the same as OEM.
 
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