1975 2.7 Pistons/Cylinders ?

[niall]

Hi
I have a early 1975 911 2.7 probably built in 74, its not a 911S not sure what model exactly.

What pistons and cylinders could this era of 911 have originally?

I am about to commence a rebuild replacing all seals bearings and piston rings, but I,ve heard some pistons and cylinders should not be taken apart and are unusable if they are!!!

Thanks for the help.
Niall

[jbell959]

Your pistons and cylinders are either Mahle or KS. More importantly they are either Nikasil or Alusil cylinders. The Nikasil cylinders have a shinny finsh and are slightly magnetic. The Alusil cylinders have a dull grey finish and are not magnetic. Some people don't recommend re-ringing the Alusil cylinders and other say it is OK. Some people also recommend not taking the pistons out of the cyllinders on a rebuild and leaving the rings alone. If you can find a good used set of Nikasil cylinders it is worth the money. Keep in mind that the pistons are not interchangeable between Nikasil and Alusil cylinders.