C145 / O300 interchangeable?

[Stan_Lindholm]

Can an O300 (A, B, C or D) be used in place of the C145 in my '52 170B? What are the differences between the A, B, C and D?

Yeah, I know it's really the same engine, just wondered about the legality of installing it -- i.e.: is it an approved engine or is there an STC?

The reason I ask is I may be looking at a major overhaul, and I've seen a few used O300's advertised.

Thanks!

[Bruce Fenstermacher]

The differences have been answered in a post buy George in the MX library titled 0-300 differences. The 0-300-A is the same as the C-145 and is interchangable on the 170 airframe. The B, C and D model will require some kind of approval. There are some STC's but most are done with one time approvals which in a past life where easier to get than now.

[doug8082a]

One of the more immediate differences is the prop flange. The C-145, O-300A, O-300B have an 8 bolt flange while the O-300C & O-300D have a 6 bolt flange. This means you can take your C-145 prop and bolt it onto the O-300A or B, but not the C or D versions.

[Stan_Lindholm]

Thanks for the replies -- they were very helpful.

Cheers,