"D' Pistons

Chefbob1 · Post by **Chefbob1** » 22 Dec 2012, 19:23

I need 2 "D" marked pistons for my 850 turbo...I have 2 "E" marked ones to trade if need be...or cash...bob

Post by **jimmy57** » 22 Dec 2012, 22:11

You do know the difference between a bore needing a D and one needing an E is two or three passes of a cylinder hone.
If a D marked bore is on an engine with more than 75000 miles an E piston probably runs with the .01-.03 skirt clearance desired with no honing.

Chefbob1 · Post by **Chefbob1** » 24 Dec 2012, 20:37

Thanks for the comment...the block we are building has the original honing marks in it.....and not sure how many miles on it...trying to build it right...what is the diameter of the different "Lettered" pistons....if you know...and thanks again for helping to educate me...I need all the help I can get...i am new to the volvo world....but love the 850 wagons...mine are all black and look like Darth Vader....bob

Post by **jimmy57** » 24 Dec 2012, 21:50

The size diff between the letters is .01 mm except for G which makes a .02mm jump from the next one down.
All these use the same rings.
They hone until they are satisfied with the bore finish and then check and select which of the standard + pistons fit that bore.
The more usual way was to have a piston to bore allowance of .01-.08mm and use one size piston. This leaves some engines noisier than others.