Super Jet Piston wall Clearance

[Germanrider]

Hello
Building up a new engine at the moment.
The cylinder is fresh bored and honed. Can’t measure the wall Clearence. The ring gap is 0,09inch which is ok for oem pistons I think. Normally I use pro-x pistons and they have a larger ring gap but on this pistons stands only 61x00 and Art hope this are oem pistons and the manual says the ring gap is okay than.
Please correct me when I am wrong.
Installed them and then I see this the wall clearance is not the some on all sites of one of the pistons. Never see that before at any engine.
What do you think?

 

[Germanrider]

Thanks for the fast answer.
Forgot a 0 so I have 0,009“ gap

The machine shop says clearance is perfect he don’t do it for the first time. I believe him.
Do you have any idea why the pistons Is so close to one side or does anyone see this before or is it perhaps normal and I have only not see it before ?

 

[Storbeck]

The piston is tapered, the top is smaller in diameter than the bottom. Piston clearance is measured across the skirts where the piston is largest, what you can see in that picture tells you nothing about the piston to cylinder wall clearance.

 

[Germanrider]

I know that it don’t tell me anything about the clearance themselfe. Do you all think I don’t have to worry about it that the piston is on one side nearer to the cylinder than on the other side ?

 

[Germanrider]

Perfect thank you so much for the fast and perfect answers

 

[MTRHEAD]

ART Brand are OEM Pistons.

ProX makes ART Pistons.

The Machinist should have measured each Piston Diameter and Bored each Cylinder according to the recommended Clearance specified by the Manufacturer. The required Clearance is noted in the Instructions that come with the New Pistons.

Ask your Machinist how much Clearance he Bored & Honed or what the Final Bore Diameter is.

Then subtract the Piston Diameter and that will be the Piston to Bore Clearance (28-30 thousandths of an Inch for OEM).

Note: Each Manufacturer has their own Clearance Requirement depending on the Metallurgy of the Piston; because different Metal Compositions and Shapes expand at different rates.

OEM Ring Gap is 8-16 thousandths of an Inch. That's 0.008" to 0.016". So you must have 0.009", not 0.09 inch.

ART is the Japanese mfg - Pro-x is a distributor not a manufacturer

 

[WFO Speedracer]

The reason you see different specs on different pistons is because some pistons are cast and some are forged, the forged pistons expand more and require more clearance, also OEM piston to wall clearance are usually set pretty low to begin with , usually on a cast piston you want .004' to .0045 piston to wall clearance