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Anyone who can tell my what difference (if there is any) there is between SS/SZ pistons and "Normal pistons" for the 1300 engine.
The parts numbers for sure are different.
A good guess from my side is that the SS/SZ ones are more "high compression" than the normal ones but how big is the difference ?.
Thanks in advance
Björn
 

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Hi Björn,

my information says 1300 normale = 8.5:1 compresion ratio
1300 veloce = 9.1:1 compresion ratio
1300 SS = 9.7:1 compresion ratio

Hope that is of some help to you.
Have a nice weekend,
Nick
 

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There were just today a set of NOS Mahle Normale pistons (8.5) on ebay that I got outbid on. The crown shape looked quite a bit lower, with resulting smaller valve cutouts, than what Centerline shows on its site for 9.1 "Normale" pistons.
Andrew
 

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Aside from the compression ratio and piston crown shape, I think the Veloce pistons were also forged instead of cast (but I'm not positive about this point).
Jim
 

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Regardless of what piston you are using (Dome shape), if you are rebuilding an SS (1300) or SZ engine I would chamfer the top edge of the piston about 3-4 mm to relieve the edge as the engine block has been shortened on these engines. If you have the old pistons, you will see how much was removed. I would then "clay" any replacement pistons to make sure there is the correct clearance in the valve pockets. Your machine shop will tell you how much is satisfactory accounting for heat expansion.
 
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