Help Me Identify My O-320 Cylinders

[nippaero]

I recently got my hands on an O-320 that was removed from a Cherokee 140. I plan on rebuilding the engine with some local help.

I have some questions on the cylinders though and I was hoping someone could help get me pointed in the right direction.

1) How can you tell if they are Plain steel or chrome plated? Two of the cylinders are marked 75868 which appears to me to be plain steel per the Lycoming parts catalog. Is there another way to tell?

2) One cylinder has a valve guide that looks different from the others. It appears to have a small impression and machined ribs. Anyone know what this is?



3) Two of the cylinders have yellow paint on them. Does this mean that they have been bored out .020" oversize?



4) Two cylinders are marked 75868 and the other two are marked LW12417. I can't seem to find reference to the LW12417. Can someone help me identify it?

[lr172]

The painted fins are a guide for the cylinder type. Sorry, but I don't know that color code system. I vaguely remember that they never paint plain steel, but may paint steel, tapered bores. Don't forget that you have material type as well at straight bores and choked bores.

Those are not machined ribs, it is a helical channel. You'll notice that it emanates from the notch. I would assume this is an aftermarket guide and the MFR put this channel there to help keep the guide well oiled, especially when the valve starts to collect deposits. Lyc's have a bad history with Exh. valves.

Larry

[az_gila]

From ECI literature -

Lycoming or ECi replacement Cylinders for Lycoming Engines:

Color Codes for the outer fin tip area between spark plug and cylinder barrel or color band between the flange and lower cooling fin are:

Standard Size Barrels:

• Engine Gray or Unpainted - Plain Steel or thru-hardened Airmotive Steel
• International Orange - Chromium type bores
• Two (2) Silver Stripes - CermiNil Process and/or Nickel+Carbide Bores
• Blue - Nitride Hardened Steel

Oversize Barrels:

• Green - Plus .010 Inch
• Yellow - Plus .020 Inch

Color codes for fin area between spark plug and rocker box are

• Engine Gray, Blue or Unpainted - Short Reach Spark Plugs
• Yellow - Long Reach Spark Plugs

--------------------------------

Two cylinders are marked 75868 and the other two are marked LW12417. I can't seem to find reference to the LW12417. Can someone help me identify it?

The Lycoming superceded part numbers list simply shows the LW12417 as a later part number for the 75868 cylinder assemblies.

[nippaero]

Thanks Gil and Larry. That helps a lot. I wondered if the grooves in the guide was to help keep oil up around the valve.

I also found that the LW12417 was superseded by the LW12416.

So it looks like two of my cylinders had been bored out .020" over. I will verify when my new cylinder bore gauge gets here from Amazon.

If you look closely there is also a white stripe below on the steel barrel. Ay idea what that means?