I have a b18c1 block with RS Machine 81.5mm pistons. What is the recommended piston to wall clearance? I know the OEM spec for b18c1 is .0004" - .0016". Talking to my machine shop, he recommended .002", but he is more of a domestic car guy...

 

Your, machinist knows what he's talking about.

 

actually he was going to do .020", but I called him and told him the OEM honda spec then he said he would do .002"

 

Rs recommends 1.25-1.5 thou.

 

I believe. 0020 is the service limit on oem pistons. Not sure if the rs machines are 100% identical to oem honda in piston materials/silicon content thus affecting their expansion rate. Smartest thing to do would be to call RS Machine and get the right answer. On oem honda pistons i like .0010.

 

I HIGHLY doubt that.

 

rs recommends honda specs

i believe one of the guys there recommended .0015, but dont take my word on that one.

 

Last ITR I assembled had .0005 on three cylinders and it was a lil tight @ .0003 in cylinder #1. Tight bish I know.

 

holly cow that is tight! anyone think i would have any problems going .002". what are the pros and cons of being tight/loose on this spec?

 

As I stated, that is honda's SERVICE Limit, meaning max clearance. Why would you want that? .0004-.0016 is oem NORMAL spec but most people like .0004-.0010.

 

0.001"