I searched and couldn't find an answer for some reason. My question is will 3.809 piston work when my machinist says the block is 3.810 without problems? My first is build and don't want to screw up. I can find a ton of 3.809 piston but trouble finding 3.810. Thanks in advance.

 

Have you already bored the block .030 over. ? Most machinist want the piston in hand to do final cut and hone.

 

Yes, pistons in hand at the machine shop is best. As advised above, this allows for the precise tailoring of the bore to each piston.

Rick

 

Nope, he said that was what it took to get the surface right. So, what to do now since piston wasn't in hand. Get it rebored?

 

I suggest mic'ing your pistons and cylinders. IIRC the last 5.3 i bored and honed, about 3 months ago, i took it out to .040 due to some rust. The pistons measured at 3.8175, we keep piston to cylinder from .0025 to .003. So if your pistons measure 3.807 to 3.8075, your cylinder can messure 3.8095 to 3.810. Metric bores (5.3 is 96mm, 5.7 is 99mm, 6.0 is 101.5mm) when converted really depend on what decimal you round up at, so measuring bore and piston are the only way to know exactly where you are at.

 

If this is an iron block 5.3, why not bore it all the way to 5.7 liters? I'm told these iron 5.3's have enough cylinder wall meat to safely and easily go to 5.7 and those pistons should be plentiful. Cost for a 5.7 piston? Within pennies of the same as a 5.3.

Rick

 

The flat tops I ended up ordering are for the 4.8 and are 96.75mm. Machinist said I should be good to go and it will bump up my compression. Still be able to run on pump gas with zero problems. Can't wait to get it together and installed. Thanks again for the input.

 

I would have gone with a LS1 piston 10 or 20 over . 20 over would be 3.918 . Usually LS1 piston flat top are cheaper than 3.8xx pistons.