In article ,
(Mike) wrote:

Hello All,

An "exhaustive" internet search regarding the 0-290G has left me with
several unanswered questions. I understand that the EAA published a
conversion guide years back that would be very helpful. In the mean
time, I am hoping some of you out there can answer any of the
following questions:

1) Which cylinders may be used (i.e. bolt-on) on the O-290G? I
understand that the stock cylinders, other 0-290 cylinders (D, D2
etc), and 0-435 may be bolted on and used.

There are two kinds of straight valve cylinders military (O-435-C) and
civilian (O-435-A) -- both are acceptable in any combination.




2) Which pistons may be used (in native/unmodified form)?

It is best to use the 3-ring pistons, rather than the old 4-ring
pistons. You can get 135 hp, if you use the O-290-D2 pistons (7.5:1,
rather than 6.5:1 compression ratio)

Piston Top Comp 2nd Comp Oil ring
125 hp 69958 62916/LW-13883p Same as #1 69401ca/68338pa
135 hp 69481 Same Same Same

3) Which cranks may be used (in native/unmodified form)? I understand
that "any" 0-320 crank may be installed without modification.

I don't know this one, as I use the O-435.


4) What "slight" modifications can be used to up the HP to 150hp?

5) Is the "converted" 0-290G still heavier than an 0-320? Why?

6) Any known sources for 0-290 parts?

El Reno Aviation
1994 S. Country Club Rd
PO Box 760
El Reno
OK 73036-0760

Ph: 1-800-521-0333

The entire top end of the straight valve O-435 series is the same as the
top end of the O-290 series. The only differences in hp are the pistons.

You can use the same tappets, lifters, push rods in O-540, )-360, etc.