my forged pistons came today...about to fit them and checked the izes...

now these are 3.642 inchs which is bigger than (92mm/3.62479 inchs)

can anyone give me so idea why this is??? ive heard they have to be bang on 92mm...is this true????

 

Sounds like your new pistons are oversize. 92.5mm if my maths is right. Just means you need the bores honed to suit remembering what clearance they need. Anyone want to add to this...?

 

ohh jesus..is there anything else ill need to check/change...i bought these thinking they were a direct replacment lol

 

anyone know where i can get my bores honed local to north wales??

 

As far as i'm aware mate, the pistons should come with a spec sheet telling you about clearance etc. It'll be down to you/machine shop whats done. Best asking someone that knows there stuff. I'm on my first engine build so learning all the way...sometimes the hard way...

I'd also check the new pistons to confirm they are 92.5mm. Believe this is the 2nd oversize. (going by Dazdavies thread).

 

3.642" is 92.50mm, so it's an over sized piston, designed so if the bores are scratched, or damaged, they can be bored/honed to get perfect surfaces.

Mark.

 

thanks guys..really appriciate the replys/info