DKW NZ 350

Hello

I need new piston rings for my NZ 350 motor. Greiner has them for sale however the only problem I am having is figuring out what size I need. Does anybody know what size I do need? I looked in the manual and they listed 3 or 4 different sizes. Thank you

Regards
Zack

Hello Zack!

That would depend upon what size (diameter) of piston or cylinder bore you'll want to fit them on. Does not your existing piston have the diameter indicated on the top surface? Otrherwise you would have to measure it.

Regards
Gorm

That would depend upon what size (diameter) of piston or cylinder bore you'll want to fit them on. Does not your existing piston have the diameter indicated on the top surface? Otrherwise you would have to measure it.

Indeed, but does any-one knows the tollerance between cylinder and piston?
So, when I have the smallest (or bigger) piston, to wich size I do have to bore the cylinder?
PS. pistonrings do also have their measures, You should use pistonrings wich belong to your (or a new) piston.

Regards
martin

Hi Martin,

The tolerance according to the ws-manual should be 0,17mm +/- 0,01mm(huge, compared with nowadays engines!). This is the tolerances for the old original German pistons.

Many of the post war pistons have the tolerance stamped on the dome of the piston and it can vary quite much depending on the manufacturer of the piston and also on the material used in the piston.

Normally a good engine repair workshop with equipment to grind the cylinder, knows quite well how the job should be done in a proper way.

// Frank

Please note also that the "Stossmass" i.e. the gap in the ring when placed inside the cylinder should be 0,4 to 0,6 mm on the NZ. Repro pistons from Italy which are quite common today need a higher "Kolbenspiel" than the original german pistons. That I have learned from experience!

Regards

MY piston does not have the size stamped on it. I looked all over it and couldnt find anything. I guess I will have to measure the existing piston ring that I have.