How to Measure, Mic, a Piston
Supertech PN# P4-MA835-N4
Factory supplied spec sheet.
They ask for a bore spec 3.287/83.50 mm, This what is your recommend bore size.
Tools needed for the procedure, Outside micrometers 3-4 inch,
But in a pinch, venire calipers will “Get you close” if just doing a quick check
A machinist standard is handy to have, so you can zero your measuring tools.
The points you want to measure 90* to the wrist pin centerline
A view of the appox pot to measure from, with venire caliper.
All 4 pistons in the box measured 3.2845
This is going to be Piston to Wall clearance, PTW, in theory. Your actual PTW will vary due to cylinder block finish.
The factory spec sheet says 3.287”/83.50 mm
The formula for converting mm to inches is
Mm x .03937 =Inches
83.50 x .03937 = 3.287395
Now to figure PTW (Theory)
3.287 – 3.2845 = .0025 PTW clearance
I am more accustomed to seeing .0035, but that is on a 85mm piston, and other brands of forged pistons.
That also be in part due to the “Phosphate dry lubricant”
From the super tech website
Finally our "phosphate dry lubricant" coating is applied to protect the rings against "micro welding" and enhance lubrication on the skirt/cylinder area.
Piston Rings are manufactured in Japan with the latest technology for high performance applications.
Quality Control: Performed after every step of the manufacturing process in climate controlled environments to ensure reliability of dimensions.