You've quoted the piston diameter of a class 1 piston without the corresponding class 1 bore measurement. A permissible class 1 bore diameter would be 3.3411 to 3.3415 inches
The piston clearance in the cylinder bore for any class of piston 1-3 should be 0.00039 to 0.00118 inches (0.010 to 0.030 mm)

 

thank you. Have you found that some zetecs have different piston sizes from the factory? They all are 2.0l but the piston differs? In mine the pistons are too small to fit stock bore. Weird,

P.s I need 84.8mm pistons, do you know where I can get them cheap?

 

are you using stock pistons? or forged pistons? cause they expand differently and thus vary in diameter requirements. just make sure ur ring gap is no greater than .014"

 

Im not using any pistons man. I need 84.8MM pistons. The stock ones are completely shit. They came that way, on the top above the rings #4 measured 3.319 and on the skirts it measured 3.335, so they where messed up from the factory because there is little to no wear on them.

So thanks I did need to know tolerance between them But now I need to find 84.8mm pistons and auto zone don't have em advance auto parts, napa no one has them. CFM and top speed have 85 mm pistons but rated for 10psi boost. And I don't need that. Atleast not on this focus.

And the gap between the stock piston and walls now is .019". And it did run like that, but not great.

 

Ok so up-date. I got pistons measuring 3.336, and my bore is 3.339 so what kind of rings do I need and where is a good place to get a set stronger then stock rings.

 

LOL, The ring section (top) part of the piston SHOULD be a diff size (smaller) on ALL pistons , you should only be measuring the piston on the "skirt" and no where else

Tom

 

Not saying your wrong Tom, but I was told that the piston should be the same size up and down.
And we measured it cause the top was worn and the skirt. We could clearly see the scratched up parts of the piston and cylinder.

If you say other wise, I think i'll talk the word of the fswerks worker that works with this stuff all day.

 

You don't really know Tom's reputation very well, do you?

 

Ummm? thats why im saying if he says different, I will take his word, the word of a FSWERKS employee. meaning> Tom. The one who works with this stuff all day.

If there is anyone's word on here i'll take, it's Toms. And a few other's.


So anyways, Ok tom well where im at now is I honed them. And there all measuring 3.339 inch, and I got 20k pistons that are 3.336 inch. Measuring only from the skirt. Is that going to be a good gap, and set up?

 

Ltes move on !

 

Ok thanks Tom, But I got that info from my dad who has done one re-build before this soo. I don't know how much he knows, but apparently he don't know everything.
And before I meant, I will take your word, the word of a FSWERKS employee. Are you not a employee of them? My bad if you're not, I was under the impression that you where a FSWERKS employee. From meeting you in FJ.


But trust Tom, I know your rep and it is very true when people say you know what your talking about. So if there was wear to the top of the piston what would you do? Or in any situation, it does not matter as long as it's not a lot, and the skirt is the size it should be?

 

LOL no I do not work for or have ANYTHING to do with fs

The top of the piston (where rings are) never tuches the Cyl wall only the skirts

Tom

 

Ok well hang on I got a pic for you to see, cause the top of my piston was rubbing right above the rings.

I don't have a good piston shot. But you can see here clearly the top of my #4 cylinder was rubbing, and you can see I had problem's with the ring's. But is this a result of worn rings that did this to the top of the piston and bore?

 

Could of done that when you removed the pistons , the tops of the pistons are smaller and cant hit the cyl wall when running

Tom