I have a very early narrow deck O-320 no suffix, that I would like to convert to 160 HP.
Lucky for me, it used the very early spline nuts to bolt the cylinders on, and therefore already has long cylinder studs in place.
The long studs are a requirement for use with the cylinder banana plates on 160 HP engines.
The only cylinder I see for use on my engine is the one having the spot faced flange (which is unacceptable for use with the banana plates)
MY Question is....
Is there a legal way to substitute cylinders to ones that allow the use of banana plates and upgrade to the high compression 160 HP pistons ( or just stay with the low compression 150HP pistons and upgrade the cylinders) without buying an STC?
It is not just the cylinders that need to be changed but carburetor, through bolts, oil coolers, and engine mounts may also need to be changed.
Finally you need 2 STC's, one to modify the engine and then another one to install it on a particular airplane model.
Probably the best thing to do is to e-mail Lyoming directly and ask them. There will, I believe be a charge for the info, though