David Fretz
I cheated and asked questions too... BUT my advice is to jump to the engine set up side of this forum and a search of OS 20 or LA 25 or LA 46
This has you spending hours of reading to finally conclude=----that many many of these, very still available engines, can run just fine right out of the box with the recommended NVA, Glow plug, Muffler, Prop, and fuel tank set up for a wide variety of models
All the work has been done to determine the appropriate CHOKE area (Venturi vs spray bar diameter)....several vendors will sell you the correct parts for not too much $$
Randy Smith sells OS LA 46s Blue printed
There are guys who swear a metal back plate is mandatory and others that learned how to live with the plastic back-plate
I have been slowly replacing all my old skool 4-2-4 engines (Fox/Enya/K&B/Veco/Johnson) for the slightly more modern OS or ASP/Magnum engines
I fun fly and do not like fiddling with props, tanks, fuel mix.....all the planes converted to ASP or OS start predictably, are set to forum recommended RPMs and fly my quirky- sport fly -NON pattern-without ANY drama....
IMO trying to make a modern High RPM engine behave like a older low RPM engine with a distinctive 4-2-4 break is achievable BUY WHY....you want 4-2-4 buy a NIB Fox 35/40 and have at it....hundreds still for sale.....better yet a $200 Enya .35 new edition if you can find it
With a slightly more modern OS, or clone, You can Stick the right fuel in it, apply the proper low(ER) pitch prop, set launch RPMs and go fly.....too easy
For a good read on a lousy weather day, look up Dirty Dan Rutherford's very lengthy description of a OS 20 in place of Fox 35 and the now ubiquitous Brett Buck Tune Up (BBTU) a euphemism for leave the damned thing alone and go fly with OUR recipe of Engine, Fuel, Prop, Tank!
I still have a Fox 35 powered RingMaster...but my others are OS 20 powered....more gooder IMO
I also highly recommend you explore the NOW no longer produced Evo .36 CL engine and if you think a larger plane some day the Randy Smith Magnum .52 is a solid easy engine to set up for something like a SV-11
I am total hack fun flyer but a top end piped Rojett is in my future to just HAVE one
Good to be king
Competing?....electric or Piped RoJett....