I have a sleeved 84.5mm B16 block...
Using CP pistons and the clearance should be around 0.003 - 0.0035"

Will that mean that i need to order 84.42mm pistons?
Or do i need to order 84.5mm and hone the block to the correct clearance?
Or will the pistons be 0.003" undersize to be used will 84.5mm block?

 

bore your block to exactly 84.500mm and your piston to wall clearance will be perfect.
Desired clearance is built into the CP piston.

 

straight outta the mans mouth

 

I mean CP's use about 0.08-0.09mm clearance
My block is bored and honed to 84.5mm, but when i checked the bore today with special tools it was 84.510mm
So my clearance will be 0.01mm bigger than it should be... Will that be fine or what ?

 

10 thousandths is very easy to make a mistake

I wouldnt go by that, maybe bring it to a shop, dont tell them the bore and ask them to measure it and give you a number, $5 and youll have a number

I dunno, even me measuring my SRP pistons with my digital vernier I get off numbers

 

Heh...
I didnt use a digital vernier.... lol
I used this: They cost $7000 a piece, and if you see the discs in the case they are for testing if the equipment need to be recalibratet etc... They were perfect..
These measure up to 0.001mm accuracy.. Ive measured my self and two other people did.. Top-Middle-Bottom and the result is 84.510mm

 

You will be fine at 84.51mm...no big deal

 

thanx....