Piston Numbers

[steves sl]

I have an early 1965 230sl. The engine has been in a crate for 5 years. The Pistons have the following numbers stamped in the top........8297.....SPoo4 ........158/024.....plus the arrow pointing to the front. I am hoping that someone can tell me what I have, only good news please.

[Benz Dr.]

I'm going to say that you have 82.97 mm pistons which I think should be standard. I think the other numbers are production reference and not so important. Pistons should be 4 ring 24 mm pins and possibly gun drilled for pin lubrication.

[drmb]

82.97 refers to 1.00 oversize,standard size is 82.00 for a 230sl engine.
The sp0.04mm is the clearance required between cylinder bore and piston skirt when reboring cylinder bore.

[Benz Dr.]

82.97 refers to 1.00 oversize,standard size is 82.00 for a 230sl engine.
The sp0.04mm is the clearance required between cylinder bore and piston skirt when reboring cylinder bore.

Sounds right to me.

[steves sl]

Thanks for the info guys. If the engine has to be bored again, how difficult will it be purchase new piston and rings? Engine #127.981-10-005407, only good news please.

[Shvegel]

I am afraid you are already at 2nd oversize.  I thought it was odd the first oversize was 1mm out when they usually go by halves.  82mm, 82,5mm, 83mm.