r100 cylinders

[lrz]

Taking the lazy route here..
I'm curious if standard bore '77 cylinders & pistons can be swapped w/ '78-'79 version. I know the later wristpins had actual circlips vs the spring-wire type, but am unaware if there is/are larger differences to consider.

Thanks.

[lrz]

Bueller,Bueller, Ferris Bueller?

[mattcfish]

Taking the lazy route here..
I'm curious if standard bore '77 cylinders & pistons can be swapped w/ '78-'79 version. I know the later wristpins had actual circlips vs the spring-wire type, but am unaware if there is/are larger differences to consider.

Thanks.

Yes. As long as the piston's diameter and bores are within spec. The rings are different if you go from Iron liners to Nikasil.

[vanzen]

Swapping cyls. will have one considering iron or Nik, O-ring or gasket.
And the Ø of the hole in the block into which it must fit ...
Often neglected about piston swapping is
squish-band profile of the piston vs head – and the compatibility that is a result ...
Yes, always match the BMW size designations (A,B, or C) when swapping pistons into cylinders
or do the math with a micrometer ...
Choice of rings will be dependent upon the bore material.

[lrz]

Vanzen, those are the exact considerations I have. What I may do is install used cylinders (iron)w/ their own pistons . I believe the stroke remains the same for those years.

I'd prefer to retain my current heads; where might I find info regarding "new" pistons (78-79) w/ original heads (77)?

[Rapid Dog]

Not to be OT, but I've got '81 Nik cylinders and '78 squishband heads, seems to work fine.
Now I'm thinking of installing non-squish dome 9.5 pistons to raise the compression from the flat top 8.2 pistons I currently have.
I've been told there should be no problem...

[George Ryals]

Rapid dog, it sounds like you would end up with a wedge shaped squish area with the wide part of the wedge towards the outside.....trapping mixture.

Chuck the pistons up in your lathe (or your friendly neighborhood machinist's) and cut a flat squish band as wide as the corresponding squish area in the head. You can cut the cylinder base or head surface to regain the little bit of lost compression.