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General Information => General => Topic started by: rallydiesel on August 21, 2007, 03:01:34 pm

Title: Piston wear pattern
Post by: rallydiesel on August 21, 2007, 03:01:34 pm

I was measuring the pistons I am replacing and noticed that they are slightly narrower from side to side. I thought pistons would tend to wear more fore/aft due to the crankshaft motion. Do I have some thing going on that I should take care of before I put my engine back together?

By the way, they are 77.48 pistons (third oversize) but are worn down at the top 77.00 side to side and about 77.10 fore/aft. The bottoms are about 77.40 all the way around. They seem to be in pretty good condition aside from the wear if anybody is interested in them.

Title: Piston wear pattern
Post by: rallydiesel on August 23, 2007, 02:53:49 pm

Anybody?

Title: Piston wear pattern
Post by: saurkraut on August 24, 2007, 06:34:09 am

You are observing the normal shape of a piston.  the sides are usually narrower than the skirts.  Typically, they are also smaller diameter at the top than the bottom.

http://www.tpub.com/machines/12g.htm

http://courses.washington.edu/engr100/All_Sections/Engine/UofWindsorManual/Piston%20Design.htm

http://www.hobbytech.com/PistonCam.htm