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Old 10-24-2013, 10:10 AM
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Stretch Stretch is offline a shield of steel
Join Date: Sep 2009
Location: Somewhere in the Netherlands
Posts: 14,461
Originally Posted by 97 SL320 View Post
Remove material from the green areas _TOWARDS_ the crown, don't increase the diameter.

Originally Posted by 1project2many View Post

What 97 SL320 is referring to is the factory's balancing method. It's a single cut to save time and money. If you look at the difference in thickness of the pin boss between that machined area and the portion toward the center of the piston, it appears substantial. I wouldn't be afraid to continue the factory operation. I would still try to identify where the differences are between pistons before metal removal.

Here's a quick sketch showing why cutting into the green line area can't be done for long

Apologies for the lack of ISO standard drawing practices!

^^^ This rough sketch shows a quarter cross section of the piston - I hope it is understandable...
Attached Thumbnails
Engine builders' advice req'd - removable piston weights?-sketch-m102-piston-cross-section.jpg  
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
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